1.
Garnet
–
Garnets are a group of silicate minerals that have been used since the Bronze Age as gemstones and abrasives. All species of garnets possess similar physical properties and crystal forms, the different species are pyrope, almandine, spessartine, grossular, uvarovite and andradite. The garnets make up two solid solution series, pyrope-almandine-spessartine and uvarovite-grossular-andradite, the word garnet comes from the 14th‑century Middle English word gernet, meaning dark red. It is derived from the Latin granatus, from granum, Garnet species are found in many colors including red, orange, yellow, green, purple, brown, blue, black, pink, and colorless, with reddish shades most common. Garnet species light transmission properties can range from the gemstone-quality transparent specimens to the varieties used for industrial purposes as abrasives. The minerals luster is categorized as vitreous or resinous, garnets are nesosilicates having the general formula X3Y23. The X site is occupied by divalent cations 2+ and the Y site by trivalent cations 3+ in an octahedral/tetrahedral framework with 4− occupying the tetrahedra. Garnets are most often found in the crystal habit, but are also commonly found in the trapezohedron habit. They crystallize in the system, having three axes that are all of equal length and perpendicular to each other. Garnets do not show cleavage, so when they fracture under stress, because the chemical composition of garnet varies, the atomic bonds in some species are stronger than in others. As a result, this group shows a range of hardness on the Mohs scale of about 6.5 to 7.5. The harder species like almandine are often used for abrasive purposes, for gem identification purposes, a pick-up response to a strong neodymium magnet separates garnet from all other natural transparent gemstones commonly used in the jewelry trade. Almandine, Fe3Al23 Pyrope, Mg3Al23 Spessartine, Mn3Al23 Almandine, sometimes incorrectly called almandite, is the modern gem known as carbuncle, the term carbuncle is derived from the Latin meaning live coal or burning charcoal. The name Almandine is a corruption of Alabanda, a region in Asia Minor where these stones were cut in ancient times, chemically, almandine is an iron-aluminium garnet with the formula Fe3Al23, the deep red transparent stones are often called precious garnet and are used as gemstones. Almandine occurs in metamorphic rocks like mica schists, associated with such as staurolite, kyanite, andalusite. Almandine has nicknames of Oriental garnet, almandine ruby, and carbuncle, Pyrope is red in color and chemically an aluminium silicate with the formula Mg3Al23, though the magnesium can be replaced in part by calcium and ferrous iron. The color of pyrope varies from red to black. A variety of pyrope from Macon County, North Carolina is a shade and has been called rhodolite
Garnet
–
Garnet
Garnet
–
A sample showing the deep red color garnet can exhibit.
Garnet
–
Crystal structure model of garnet
Garnet
–
Almandine in metamorphic rock
2.
Chemical formula
–
These are limited to a single typographic line of symbols, which may include subscripts and superscripts. A chemical formula is not a name, and it contains no words. Although a chemical formula may imply certain simple chemical structures, it is not the same as a full chemical structural formula. Chemical formulas can fully specify the structure of only the simplest of molecules and chemical substances, the simplest types of chemical formulas are called empirical formulas, which use letters and numbers indicating the numerical proportions of atoms of each type. Molecular formulas indicate the numbers of each type of atom in a molecule. For example, the formula for glucose is CH2O, while its molecular formula is C6H12O6. This is possible if the relevant bonding is easy to show in one dimension, an example is the condensed molecular/chemical formula for ethanol, which is CH3-CH2-OH or CH3CH2OH. For reasons of structural complexity, there is no condensed chemical formula that specifies glucose, chemical formulas may be used in chemical equations to describe chemical reactions and other chemical transformations, such as the dissolving of ionic compounds into solution. A chemical formula identifies each constituent element by its chemical symbol, in empirical formulas, these proportions begin with a key element and then assign numbers of atoms of the other elements in the compound, as ratios to the key element. For molecular compounds, these numbers can all be expressed as whole numbers. For example, the formula of ethanol may be written C2H6O because the molecules of ethanol all contain two carbon atoms, six hydrogen atoms, and one oxygen atom. Some types of compounds, however, cannot be written with entirely whole-number empirical formulas. An example is boron carbide, whose formula of CBn is a variable non-whole number ratio with n ranging from over 4 to more than 6.5. When the chemical compound of the consists of simple molecules. These types of formulas are known as molecular formulas and condensed formulas. A molecular formula enumerates the number of atoms to reflect those in the molecule, so that the formula for glucose is C6H12O6 rather than the glucose empirical formula. However, except for very simple substances, molecular chemical formulas lack needed structural information, for simple molecules, a condensed formula is a type of chemical formula that may fully imply a correct structural formula. For example, ethanol may be represented by the chemical formula CH3CH2OH
Chemical formula
–
Al 2 (SO 4) 3
3.
Crystal system
–
In crystallography, the terms crystal system, crystal family and lattice system each refer to one of several classes of space groups, lattices, point groups or crystals. Informally, two crystals are in the crystal system if they have similar symmetries, though there are many exceptions to this. Space groups and crystals are divided into seven crystal systems according to their point groups, five of the crystal systems are essentially the same as five of the lattice systems, but the hexagonal and trigonal crystal systems differ from the hexagonal and rhombohedral lattice systems. The six crystal families are formed by combining the hexagonal and trigonal crystal systems into one hexagonal family, a lattice system is a class of lattices with the same set of lattice point groups, which are subgroups of the arithmetic crystal classes. The 14 Bravais lattices are grouped into seven lattice systems, triclinic, monoclinic, orthorhombic, tetragonal, rhombohedral, hexagonal, in a crystal system, a set of point groups and their corresponding space groups are assigned to a lattice system. Of the 32 point groups that exist in three dimensions, most are assigned to only one system, in which case both the crystal and lattice systems have the same name. However, five point groups are assigned to two systems, rhombohedral and hexagonal, because both exhibit threefold rotational symmetry. These point groups are assigned to the crystal system. In total there are seven crystal systems, triclinic, monoclinic, orthorhombic, tetragonal, trigonal, hexagonal, a crystal family is determined by lattices and point groups. It is formed by combining crystal systems which have space groups assigned to a lattice system. In three dimensions, the families and systems are identical, except the hexagonal and trigonal crystal systems. In total there are six families, triclinic, monoclinic, orthorhombic, tetragonal, hexagonal. Spaces with less than three dimensions have the number of crystal systems, crystal families and lattice systems. In one-dimensional space, there is one crystal system, in 2D space, there are four crystal systems, oblique, rectangular, square and hexagonal. The relation between three-dimensional crystal families, crystal systems and lattice systems is shown in the table, Note. To avoid confusion of terminology, the term trigonal lattice is not used, if the original structure and inverted structure are identical, then the structure is centrosymmetric. Still, even for non-centrosymmetric case, inverted structure in some cases can be rotated to align with the original structure and this is the case of non-centrosymmetric achiral structure. If the inverted structure cannot be rotated to align with the structure, then the structure is chiral
Crystal system
–
Hexagonal
hanksite crystal, with three-fold c-axis symmetry
Crystal system
–
The
diamond crystal structure belongs to the face-centered
cubic lattice, with a repeated 2-atom pattern.
4.
Cubic crystal system
–
In crystallography, the cubic crystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals, there are three main varieties of these crystals, Primitive cubic Body-centered cubic, Face-centered cubic Each is subdivided into other variants listed below. Note that although the cell in these crystals is conventionally taken to be a cube. This is related to the fact that in most cubic crystal systems, a classic isometric crystal has square or pentagonal faces. The three Bravais lattices in the crystal system are, The primitive cubic system consists of one lattice point on each corner of the cube. Each atom at a point is then shared equally between eight adjacent cubes, and the unit cell therefore contains in total one atom. The body-centered cubic system has one point in the center of the unit cell in addition to the eight corner points. It has a net total of 2 lattice points per unit cell, Each sphere in a cF lattice has coordination number 12. The face-centered cubic system is related to the hexagonal close packed system. The plane of a cubic system is a hexagonal grid. Attempting to create a C-centered cubic crystal system would result in a simple tetragonal Bravais lattice, there are a total 36 cubic space groups. Other terms for hexoctahedral are, normal class, holohedral, ditesseral central class, a simple cubic unit cell has a single cubic void in the center. Additionally, there are 24 tetrahedral voids located in a square spacing around each octahedral void and these tetrahedral voids are not local maxima and are not technically voids, but they do occasionally appear in multi-atom unit cells. A face-centered cubic unit cell has eight tetrahedral voids located midway between each corner and the center of the cell, for a total of eight net tetrahedral voids. One important characteristic of a structure is its atomic packing factor. This is calculated by assuming all the atoms are identical spheres. The atomic packing factor is the proportion of space filled by these spheres, assuming one atom per lattice point, in a primitive cubic lattice with cube side length a, the sphere radius would be a⁄2 and the atomic packing factor turns out to be about 0.524. Similarly, in a bcc lattice, the atomic packing factor is 0.680, as a rule, since atoms in a solid attract each other, the more tightly packed arrangements of atoms tend to be more common
Cubic crystal system
–
A rock containing three crystals of
pyrite (FeS 2). The crystal structure of pyrite is primitive cubic, and this is reflected in the cubic symmetry of its natural
crystal facets.
Cubic crystal system
–
A network model of a primitive cubic system.
5.
Crystal class
–
For a periodic crystal, the group must also be consistent with maintenance of the three-dimensional translational symmetry that defines crystallinity. The macroscopic properties of a crystal would look exactly the same before, in the classification of crystals, each point group is also known as a crystal class. There are infinitely many three-dimensional point groups, however, the crystallographic restriction of the infinite families of general point groups results in there being only 32 crystallographic point groups. These 32 point groups are one-and-the same as the 32 types of morphological crystalline symmetries derived in 1830 by Johann Friedrich Christian Hessel from a consideration of observed crystal forms, the point groups are denoted by their component symmetries. There are a few standard notations used by crystallographers, mineralogists, for the correspondence of the two systems below, see crystal system. In Schoenflies notation, point groups are denoted by a symbol with a subscript. The symbols used in crystallography mean the following, Cn indicates that the group has a rotation axis. Cnh is Cn with the addition of a plane perpendicular to the axis of rotation. Cnv is Cn with the addition of n mirror planes parallel to the axis of rotation, s2n denotes a group that contains only a 2n-fold rotation-reflection axis. Dn indicates that the group has a rotation axis plus n twofold axes perpendicular to that axis. Dnh has, in addition, a plane perpendicular to the n-fold axis. Dnd has, in addition to the elements of Dn, mirror planes parallel to the n-fold axis, the letter T indicates that the group has the symmetry of a tetrahedron. Td includes improper rotation operations, T excludes improper rotation operations, the letter O indicates that the group has the symmetry of an octahedron, with or without improper operations. Due to the crystallographic restriction theorem, n =1,2,3,4, d4d and D6d are actually forbidden because they contain improper rotations with n=8 and 12 respectively. The 27 point groups in the table plus T, Td, Th, O, an abbreviated form of the Hermann–Mauguin notation commonly used for space groups also serves to describe crystallographic point groups. Group names are Molecular symmetry Point group Space group Point groups in three dimensions Crystal system Point-group symbols in International Tables for Crystallography,12.1, pp. 818-820 Names and symbols of the 32 crystal classes in International Tables for Crystallography. 10.1, p.794 Pictorial overview of the 32 groups Point Groups - Flow Chart Inorganic Chemistry Group Theory Practice Problems
Crystal class
–
Class
6.
H-M symbol
–
In geometry, Hermann–Mauguin notation is used to represent the symmetry elements in point groups, plane groups and space groups. It is named after the German crystallographer Carl Hermann and the French mineralogist Charles-Victor Mauguin and this notation is sometimes called international notation, because it was adopted as standard by the International Tables For Crystallography since their first edition in 1935. Rotation axes are denoted by a number n —1,2,3,4,5,6,7,8, for improper rotations, Hermann–Mauguin symbols show rotoinversion axes, unlike Schoenflies and Shubnikov notations, where the preference is given to rotation-reflection axes. The rotoinversion axes are represented by the number with a macron. The symbol for a plane is m. The direction of the plane is defined as the direction of perpendicular to the face. Hermann–Mauguin symbols show symmetrically non-equivalent axes and planes, the direction of a symmetry element is represented by its position in the Hermann–Mauguin symbol. If a rotation axis n and a mirror plane m have the same direction, if two or more axes have the same direction, the axis with higher symmetry is shown. Higher symmetry means that the axis generates a pattern with more points, for example, rotation axes 3,4,5,6,7,8 generate 3-, 4-, 5-, 6-, 7-, 8-point patterns, respectively. Improper rotation axes 3,4,5,6,7,8 generate 6-, 4-, 10-, 6-, 14-, 8-point patterns, if both, the rotation and rotoinversion axes satisfy the previous rule, the rotation axis should be chosen. For example, 3/m combination is equivalent to 6, since 6 generates 6 points, and 3 generates only 3,6 should be written instead of 3/m. Analogously, in the case when both 3 and 3 axes are present,3 should be written, however we write 4/m, not 4/m, because both 4 and 4 generate four points. Finally, the Hermann–Mauguin symbol depends on the type of the group and these groups may contain only two-fold axes, mirror planes, and inversion center. These are the point groups 1 and 1,2, m, and 2/m, and 222, 2/m2/m2/m. If the symbol contains three positions, then they denote symmetry elements in the x, y, z direction, First position — primary direction — z direction, assigned to the higher-order axis. Second position — symmetrically equivalent secondary directions, which are perpendicular to the z-axis and these can be 2, m, or 2/m. Third position — symmetrically equivalent tertiary directions, passing between secondary directions and these can be 2, m, or 2/m. These are the crystallographic groups 3,32, 3m,3, and 32/m,4,422, 4mm,4, 42m, 4/m, and 4/m2/m2/m, and 6,622, 6mm,6, 6m2, 6/m, and 6/m2/m2/m
H-M symbol
–
Contents
7.
Space group
–
In mathematics, physics and chemistry, a space group is the symmetry group of a configuration in space, usually in three dimensions. In three dimensions, there are 219 distinct types, or 230 if chiral copies are considered distinct, Space groups are also studied in dimensions other than 3 where they are sometimes called Bieberbach groups, and are discrete cocompact groups of isometries of an oriented Euclidean space. In crystallography, space groups are called the crystallographic or Fedorov groups. A definitive source regarding 3-dimensional space groups is the International Tables for Crystallography, in 1879 Leonhard Sohncke listed the 65 space groups whose elements preserve the orientation. More accurately, he listed 66 groups, but Fedorov and Schönflies both noticed that two of them were really the same, the space groups in 3 dimensions were first enumerated by Fedorov, and shortly afterwards were independently enumerated by Schönflies. The correct list of 230 space groups was found by 1892 during correspondence between Fedorov and Schönflies, burckhardt describes the history of the discovery of the space groups in detail. The space groups in three dimensions are made from combinations of the 32 crystallographic point groups with the 14 Bravais lattices, the combination of all these symmetry operations results in a total of 230 different space groups describing all possible crystal symmetries. The elements of the space group fixing a point of space are rotations, reflections, the identity element, the translations form a normal abelian subgroup of rank 3, called the Bravais lattice. There are 14 possible types of Bravais lattice, the quotient of the space group by the Bravais lattice is a finite group which is one of the 32 possible point groups. Translation is defined as the moves from one point to another point. A glide plane is a reflection in a plane, followed by a parallel with that plane. This is noted by a, b or c, depending on which axis the glide is along. There is also the n glide, which is a glide along the half of a diagonal of a face, and the d glide, the latter is called the diamond glide plane as it features in the diamond structure. In 17 space groups, due to the centering of the cell, the glides occur in two directions simultaneously, i. e. the same glide plane can be called b or c, a or b. For example, group Abm2 could be also called Acm2, group Ccca could be called Cccb, in 1992, it was suggested to use symbol e for such planes. The symbols for five groups have been modified, A screw axis is a rotation about an axis. These are noted by a number, n, to describe the degree of rotation, the degree of translation is then added as a subscript showing how far along the axis the translation is, as a portion of the parallel lattice vector. So,21 is a rotation followed by a translation of 1/2 of the lattice vector
Space group
–
The space group of hexagonal H 2 O ice is P6 3 / mmc. The first m indicates the mirror plane perpendicular to the c-axis (a), the second m indicates the mirror planes parallel to the c-axis (b) and the c indicates the glide planes (b) and (c). The black boxes outline the unit cell.
8.
Crystal structure
–
In crystallography, crystal structure is a description of the ordered arrangement of atoms, ions or molecules in a crystalline material. Ordered structures occur from the nature of the constituent particles to form symmetric patterns that repeat along the principal directions of three-dimensional space in matter. The smallest group of particles in the material that constitutes the pattern is the unit cell of the structure. The unit cell completely defines the symmetry and structure of the crystal lattice. The repeating patterns are said to be located at the points of the Bravais lattice, the lengths of the principal axes, or edges, of the unit cell and the angles between them are the lattice constants, also called lattice parameters. The symmetry properties of the crystal are described by the concept of space groups, all possible symmetric arrangements of particles in three-dimensional space may be described by the 230 space groups. The crystal structure and symmetry play a role in determining many physical properties, such as cleavage, electronic band structure. The crystal structure of a material can be described in terms of its unit cell, the unit cell is a box containing one or more atoms arranged in three dimensions. The unit cells stacked in three-dimensional space describe the arrangement of atoms of the crystal. Commonly, atomic positions are represented in terms of fractional coordinates, the atom positions within the unit cell can be calculated through application of symmetry operations to the asymmetric unit. The asymmetric unit refers to the smallest possible occupation of space within the unit cell and this does not, however imply that the entirety of the asymmetric unit must lie within the boundaries of the unit cell. Symmetric transformations of atom positions are calculated from the group of the crystal structure. Vectors and planes in a lattice are described by the three-value Miller index notation. It uses the indices ℓ, m, and n as directional parameters, which are separated by 90°, by definition, the syntax denotes a plane that intercepts the three points a1/ℓ, a2/m, and a3/n, or some multiple thereof. That is, the Miller indices are proportional to the inverses of the intercepts of the plane with the unit cell, if one or more of the indices is zero, it means that the planes do not intersect that axis. A plane containing a coordinate axis is translated so that it no longer contains that axis before its Miller indices are determined, the Miller indices for a plane are integers with no common factors. Negative indices are indicated with horizontal bars, as in, in an orthogonal coordinate system for a cubic cell, the Miller indices of a plane are the Cartesian components of a vector normal to the plane. Likewise, the planes are geometric planes linking nodes
Crystal structure
–
Quartz is one of the several thermodynamically stable
crystalline forms of
silica, SiO 2. The most important forms of silica include:
α-quartz,
β-quartz,
tridymite,
cristobalite,
coesite, and
stishovite.
Crystal structure
9.
Crystal habit
–
In mineralogy, crystal habit is the characteristic external shape of an individual crystal or crystal group. A single crystals habit is a description of its shape and its crystallographic forms. Recognizing the habit may help in identifying a mineral, when the faces are well-developed due to uncrowded growth a crystal is called euhedral, one with partially developed faces is subhedral, and one with undeveloped crystal faces is called anhedral. The long axis of a quartz crystal typically has a six-sided prismatic habit with parallel opposite faces. Aggregates can be formed of individual crystals with euhedral to anhedral grains, the arrangement of crystals within the aggregate can be characteristic of certain minerals. For example, minerals used for asbestos insulation often grow in a fibrous habit, the terms used by mineralogists to report crystal habits describe the typical appearance of an ideal mineral. Recognizing the habit can aid in identification as some habits are characteristic, most minerals, however, do not display ideal habits due to conditions during crystallization. Minerals belonging to the crystal system do not necessarily exhibit the same habit. Some habits of a mineral are unique to its variety and locality, For example, while most sapphires form elongate barrel-shaped crystals, ordinarily, the latter habit is seen only in ruby. Sapphire and ruby are both varieties of the mineral, corundum. Some minerals may replace other existing minerals while preserving the originals habit, a classic example is tigers eye quartz, crocidolite asbestos replaced by silica. While quartz typically forms prismatic crystals, in tigers eye the original fibrous habit of crocidolite is preserved, the names of crystal habits are derived from, Predominant crystal faces. Abnormal grain growth Grain growth Crystallization
Crystal habit
–
Pyrite sun (or dollar) in laminated shale matrix. Between tightly spaced layers of shale, the aggregate was forced to grow in a laterally compressed, radiating manner. Under normal conditions, pyrite would form cubes or pyritohedrons.
Crystal habit
–
Goethite replacing
pyrite cubes
Crystal habit
–
Acicular
Crystal habit
–
Amygdaloidal
10.
Cleavage (crystal)
–
Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite crystallographic structural planes. Cleavage forms parallel to planes, Basal or pinacoidal cleavage occurs when there is only one cleavage plane. Mica also has basal cleavage, this is why mica can be peeled into thin sheets, cubic cleavage occurs on when there are three cleavage planes intersecting at 90 degrees. Halite has cubic cleavage, and therefore, when halite crystals are broken, octahedral cleavage occurs when there are four cleavage planes in a crystal. Octahedral cleavage is common for semiconductors, rhombohedral cleavage occurs when there are three cleavage planes intersecting at angles that are not 90 degrees. Prismatic cleavage occurs when there are two planes in a crystal. Dodecahedral cleavage occurs when there are six cleavage planes in a crystal, crystal parting occurs when minerals break along planes of structural weakness due to external stress or along twin composition planes. Parting breaks are very similar in appearance to cleavage, but only due to stress. Examples include magnetite which shows octahedral parting, the parting of corundum. Cleavage is a property traditionally used in mineral identification, both in hand specimen and microscopic examination of rock and mineral studies. As an example, the angles between the cleavage planes for the pyroxenes and the amphiboles are diagnostic. Crystal cleavage is of importance in the electronics industry and in the cutting of gemstones. Precious stones are generally cleaved by impact, as in diamond cutting, synthetic single crystals of semiconductor materials are generally sold as thin wafers which are much easier to cleave. Elemental semiconductors are diamond cubic, a group for which octahedral cleavage is observed. This means that some orientations of wafer allow near-perfect rectangles to be cleaved, most other commercial semiconductors can be made in the related zinc blende structure, with similar cleavage planes. Cleavage Mineral galleries, Mineral properties – Cleavage
Cleavage (crystal)
–
Green
fluorite with prominent cleavage.
Cleavage (crystal)
–
Biotite with basal cleavage.
11.
Fracture (mineralogy)
–
In the field of mineralogy, fracture is the texture and shape of a rocks surface formed when a mineral is fractured. Minerals often have a highly distinctive fracture, making it a feature used in their identification. Fracture differs from cleavage in that the latter involves clean splitting along the planes of the minerals crystal structure. All minerals exhibit fracture, but when very strong cleavage is present, conchoidal fracture breakage that resembles the concentric ripples of a mussel shell. It often occurs in amorphous or fine-grained minerals such as flint, opal or obsidian, subconchoidal fracture is similar to conchoidal fracture, but with less significant curvature. Earthy fracture is reminiscent of freshly broken soil and it is frequently seen in relatively soft, loosely bound minerals, such as limonite, kaolinite and aluminite. Hackly fracture is jagged, sharp and not even and it occurs when metals are torn, and so is often encountered in native metals such as copper and silver. Splintery fracture comprises sharp elongated points and it is particularly seen in fibrous minerals such as chrysotile, but may also occur in non-fibrous minerals such as kyanite. Uneven fracture is a surface or one with random irregularities. It occurs in a range of minerals including arsenopyrite, pyrite and magnetite. Rudolf Duda and Lubos Rejl, Minerals of the World http, //www. galleries. com/minerals/property/fracture. htm
Fracture (mineralogy)
–
Obsidian
Fracture (mineralogy)
–
Limonite
Fracture (mineralogy)
–
Native copper
Fracture (mineralogy)
–
Chrysotile
12.
Mohs scale of mineral hardness
–
The Mohs scale of mineral hardness is a qualitative ordinal scale characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. Created in 1812 by German geologist and mineralogist Friedrich Mohs, it is one of several definitions of hardness in materials science, while greatly facilitating the identification of minerals in the field, the Mohs scale does not show how well hard materials perform in an industrial setting. Despite its lack of precision, the Mohs scale is highly relevant for field geologists, the Mohs scale hardness of minerals can be commonly found in reference sheets. Reference materials may be expected to have a uniform Mohs hardness, the Mohs scale of mineral hardness is based on the ability of one natural sample of mineral to scratch another mineral visibly. The samples of matter used by Mohs are all different minerals, Minerals are pure substances found in nature. Rocks are made up of one or more minerals, as the hardest known naturally occurring substance when the scale was designed, diamonds are at the top of the scale. The hardness of a material is measured against the scale by finding the hardest material that the material can scratch. For example, if material is scratched by apatite but not by fluorite. Scratching a material for the purposes of the Mohs scale means creating non-elastic dislocations visible to the naked eye, frequently, materials that are lower on the Mohs scale can create microscopic, non-elastic dislocations on materials that have a higher Mohs number. The Mohs scale is an ordinal scale. For example, corundum is twice as hard as topaz, the table below shows the comparison with the absolute hardness measured by a sclerometer, with pictorial examples. On the Mohs scale, a streak plate has a hardness of 7.0, using these ordinary materials of known hardness can be a simple way to approximate the position of a mineral on the scale. The table below incorporates additional substances that may fall between levels, Comparison between Hardness and Hardness, Mohs hardness of elements is taken from G. V, samsonov in Handbook of the physicochemical properties of the elements, IFI-Plenum, New York, USA,1968. The Hardness of Minerals and Rocks
Mohs scale of mineral hardness
Mohs scale of mineral hardness
Mohs scale of mineral hardness
Mohs scale of mineral hardness
13.
Lustre (mineralogy)
–
Lustre or luster is the way light interacts with the surface of a crystal, rock, or mineral. The word traces its origins back to the latin lux, meaning light, a range of terms are used to describe lustre, such as earthy, metallic, greasy, and silky. Similarly, the term refers to a glassy lustre. A list of terms is given below. Lustre varies over a continuum, and so there are no rigid boundaries between the different types of lustre. The terms are frequently combined to describe types of lustre. Some minerals exhibit unusual optical phenomena, such as asterism or chatoyancy, a list of such phenomena is given below. Adamantine minerals possess a superlative lustre, which is most notably seen in diamond, such minerals are transparent or translucent, and have a high refractive index. Minerals with an adamantine lustre are uncommon, with examples being cerussite. Minerals with a degree of lustre are referred to as subadamantine, with some examples being garnet. Dull minerals exhibit little to no lustre, due to coarse granulations which scatter light in all directions, a distinction is sometimes drawn between dull minerals and earthy minerals, with the latter being coarser, and having even less lustre. Greasy minerals resemble fat or grease, a greasy lustre often occurs in minerals containing a great abundance of microscopic inclusions, with examples including opal and cordierite. Many minerals with a greasy lustre also feel greasy to the touch, metallic minerals have the lustre of polished metal, and with ideal surfaces will work as a reflective surface. Examples include galena, pyrite and magnetite, pearly minerals consist of thin transparent co-planar sheets. Light reflecting from these layers give them a lustre reminiscent of pearls, such minerals possess perfect cleavage, with examples including muscovite and stilbite. Resinous minerals have the appearance of resin, chewing gum or plastic, a principal example is amber, which is a form of fossilized resin. Silky minerals have an arrangement of extremely fine fibres, giving them a lustre reminiscent of silk. Examples include asbestos, ulexite and the satin spar variety of gypsum, a fibrous lustre is similar, but has a coarser texture
Lustre (mineralogy)
–
Cut diamonds.
Lustre (mineralogy)
–
Kaolinite
Lustre (mineralogy)
–
Moss
opal
Lustre (mineralogy)
–
Pyrite
14.
Streak (mineralogy)
–
The streak of a mineral is the color of the powder produced when it is dragged across an un-weathered surface. If no streak seems to be made, the streak is said to be white or colorless. Streak is particularly important as a diagnostic for opaque and colored materials and it is less useful for silicate minerals, most of which have a white streak or are too hard to powder easily. The apparent color of a mineral can vary widely because of impurities or a disturbed macroscopic crystal structure. Small amounts of an impurity that strongly absorbs a particular wavelength can radically change the wavelengths of light that are reflected by the specimen, and thus change the apparent color. However, when the specimen is dragged to produce a streak, it is broken into randomly oriented microscopic crystals, the surface across which the mineral is dragged is called a streak plate, and is generally made of unglazed porcelain tile. In the absence of a plate, the unglazed underside of a porcelain bowl or vase or the back of a glazed tile will work. Sometimes a streak is more easily or accurately described by comparing it with the streak made by another streak plate. Because the trail left behind results from the mineral being crushed into powder, in case of harder minerals, the color of the powder can be determined by filing or crushing with a hammer a small sample, which is then usually rubbed on a streak plate. Most minerals that are harder have a white streak. Some minerals leave a similar to their natural color, such as cinnabar. Other minerals leave surprising colors, such as fluorite, which always has a streak, although it can appear in purple, blue, yellow. Hematite, which is black in appearance, leaves a red streak which accounts for its name, galena, which can be similar in appearance to hematite, is easily distinguished by its gray streak. Hamilton, W. R. Cambridge Guide to Minerals, Rocks, the Encyclopedia of Gemstones and Minerals. New York, Facts on File. p.251, physical Characteristics of Minerals, at Introduction to Mineralogy by Andrea Bangert What is Streak
Streak (mineralogy)
–
Streak plates with
pyrite (left) and
rhodochrosite (right)
15.
Transparency and translucency
–
In the field of optics, transparency is the physical property of allowing light to pass through the material without being scattered. On a macroscopic scale, the photons can be said to follow Snells Law, in other words, a translucent medium allows the transport of light while a transparent medium not only allows the transport of light but allows for image formation. The opposite property of translucency is opacity, transparent materials appear clear, with the overall appearance of one color, or any combination leading up to a brilliant spectrum of every color. When light encounters a material, it can interact with it in different ways. These interactions depend on the wavelength of the light and the nature of the material, photons interact with an object by some combination of reflection, absorption and transmission. Some materials, such as glass and clean water, transmit much of the light that falls on them and reflect little of it. Many liquids and aqueous solutions are highly transparent, absence of structural defects and molecular structure of most liquids are mostly responsible for excellent optical transmission. Materials which do not transmit light are called opaque, many such substances have a chemical composition which includes what are referred to as absorption centers. Many substances are selective in their absorption of light frequencies. They absorb certain portions of the spectrum while reflecting others. The frequencies of the spectrum which are not absorbed are either reflected or transmitted for our physical observation and this is what gives rise to color. The attenuation of light of all frequencies and wavelengths is due to the mechanisms of absorption. Transparency can provide almost perfect camouflage for animals able to achieve it and this is easier in dimly-lit or turbid seawater than in good illumination. Many marine animals such as jellyfish are highly transparent, at the atomic or molecular level, physical absorption in the infrared portion of the spectrum depends on the frequencies of atomic or molecular vibrations or chemical bonds, and on selection rules. Nitrogen and oxygen are not greenhouse gases because there is no absorption because there is no molecular dipole moment. With regard to the scattering of light, the most critical factor is the scale of any or all of these structural features relative to the wavelength of the light being scattered. Primary material considerations include, Crystalline structure, whether or not the atoms or molecules exhibit the long-range order evidenced in crystalline solids, glassy structure, scattering centers include fluctuations in density or composition. Microstructure, scattering centers include internal surfaces such as boundaries, crystallographic defects
Transparency and translucency
–
Dichroic filters are created using optically transparent materials.
Transparency and translucency
–
Translucency of a material being used to highlight the structure of a photographic subject
Transparency and translucency
–
Meiningen Catholic Church, 20th century glass
Transparency and translucency
–
A laser beam bouncing down an
acrylic rod, illustrating the total internal reflection of light in a multimode optical fiber
16.
Specific gravity
–
This page is about the measurement using water as a reference. For a general use of gravity, see relative density. See intensive property for the property implied by specific, Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance. The reference substance is always water at its densest for liquids. Nonetheless, the temperature and pressure must be specified for both the sample and the reference, pressure is nearly always 1 atm. Temperatures for both sample and reference vary from industry to industry, in British beer brewing, the practice for specific gravity as specified above is to multiply it by 1000. Being a ratio of densities, specific gravity is a dimensionless quantity, Specific gravity varies with temperature and pressure, reference and sample must be compared at the same temperature and pressure or be corrected to a standard reference temperature and pressure. Substances with a gravity of 1 are neutrally buoyant in water. Those with SG greater than 1 are denser than water and will, disregarding surface tension effects and those with an SG less than 1 are less dense than water and will float on it. In scientific work, the relationship of mass to volume is expressed directly in terms of the density of the substance under study. It is in industry where specific gravity finds wide application, often for historical reasons. True specific gravity can be expressed mathematically as, S G true = ρ sample ρ H2 O where ρ sample is the density of the sample, the density of water varies with temperature and pressure as does the density of the sample. So it is necessary to specify the temperatures and pressures at which the densities or weights were determined and it is nearly always the case that measurements are made at 1 nominal atmosphere. For true specific gravity calculations, air pressure must be considered, temperatures are specified by the notation with T s representing the temperature at which the samples density was determined and T r the temperature at which the reference density is specified. For example, SG would be understood to mean that the density of the sample was determined at 20°C and of the water at 4°C. Taking into account different sample and reference temperatures, we note that, while S G H2 O =1.000000, it is also the case that S G H2 O =0.998203 /0.999840 =0.998363. Here, temperature is being specified using the current ITS-90 scale, on the previous IPTS-68 scale, the densities at 20 °C and 4 °C are 0.9982071 and 0.9999720 respectively, resulting in an SG value for water of 0.9982343. For example, in the industry, the Plato table lists sucrose concentration by weight against true SG
Specific gravity
–
Testing specific gravity of fuel.
17.
Refractive index
–
In optics, the refractive index or index of refraction n of a material is a dimensionless number that describes how light propagates through that medium. It is defined as n = c v, where c is the speed of light in vacuum, for example, the refractive index of water is 1.333, meaning that light travels 1.333 times faster in a vacuum than it does in water. The refractive index determines how light is bent, or refracted. The refractive indices also determine the amount of light that is reflected when reaching the interface, as well as the angle for total internal reflection. This implies that vacuum has a index of 1. The refractive index varies with the wavelength of light and this is called dispersion and causes the splitting of white light into its constituent colors in prisms and rainbows, and chromatic aberration in lenses. Light propagation in absorbing materials can be described using a refractive index. The imaginary part then handles the attenuation, while the real part accounts for refraction, the concept of refractive index is widely used within the full electromagnetic spectrum, from X-rays to radio waves. It can also be used with wave phenomena such as sound, in this case the speed of sound is used instead of that of light and a reference medium other than vacuum must be chosen. Thomas Young was presumably the person who first used, and invented, at the same time he changed this value of refractive power into a single number, instead of the traditional ratio of two numbers. The ratio had the disadvantage of different appearances, newton, who called it the proportion of the sines of incidence and refraction, wrote it as a ratio of two numbers, like 529 to 396. Hauksbee, who called it the ratio of refraction, wrote it as a ratio with a fixed numerator, hutton wrote it as a ratio with a fixed denominator, like 1.3358 to 1. Young did not use a symbol for the index of refraction, in the next years, others started using different symbols, n, m, and µ. For visible light most transparent media have refractive indices between 1 and 2, a few examples are given in the adjacent table. These values are measured at the yellow doublet D-line of sodium, with a wavelength of 589 nanometers, gases at atmospheric pressure have refractive indices close to 1 because of their low density. Almost all solids and liquids have refractive indices above 1.3, aerogel is a very low density solid that can be produced with refractive index in the range from 1.002 to 1.265. Moissanite lies at the end of the range with a refractive index as high as 2.65. Most plastics have refractive indices in the range from 1.3 to 1.7, for infrared light refractive indices can be considerably higher
Refractive index
–
Thomas Young coined the term index of refraction.
Refractive index
–
A
ray of light being
refracted in a plastic block.
Refractive index
–
Diamonds have a very high refractive index of 2.42.
Refractive index
–
A
split-ring resonator array arranged to produce a negative index of refraction for
microwaves.
18.
Absorption spectroscopy
–
Absorption spectroscopy refers to spectroscopic techniques that measure the absorption of radiation, as a function of frequency or wavelength, due to its interaction with a sample. The sample absorbs energy, i. e. photons, from the radiating field, the intensity of the absorption varies as a function of frequency, and this variation is the absorption spectrum. Absorption spectroscopy is performed across the electromagnetic spectrum, Infrared and ultraviolet-visible spectroscopy are particularly common in analytical applications. Absorption spectroscopy is employed in studies of molecular and atomic physics, astronomical spectroscopy. There are a range of experimental approaches for measuring absorption spectra. The most common arrangement is to direct a beam of radiation at a sample. The transmitted energy can be used to calculate the absorption, the source, sample arrangement and detection technique vary significantly depending on the frequency range and the purpose of the experiment. A materials absorption spectrum is the fraction of incident radiation absorbed by the material over a range of frequencies, the absorption spectrum is primarily determined by the atomic and molecular composition of the material. Radiation is more likely to be absorbed at frequencies that match the difference between two quantum mechanical states of the molecules. The absorption that occurs due to a transition between two states is referred to as a line and a spectrum is typically composed of many lines. The frequencies where absorption lines occur, as well as their relative intensities, primarily depend on the electronic, the frequencies will also depend on the interactions between molecules in the sample, the crystal structure in solids, and on several environmental factors. The lines will also have a width and shape that are determined by the spectral density or the density of states of the system. Absorption lines are classified by the nature of the quantum mechanical change induced in the molecule or atom. Rotational lines, for instance, occur when the state of a molecule is changed. Rotational lines are found in the microwave spectral region. Vibrational lines correspond to changes in the state of the molecule and are typically found in the infrared region. Electronic lines correspond to a change in the state of an atom or molecule and are typically found in the visible. X-ray absorptions are associated with the excitation of inner shell electrons in atoms and these changes can also be combined, leading to new absorption lines at the combined energy of the two changes
Absorption spectroscopy
–
An example of applying Absorption spectroscopy is the first direct detection and chemical analysis of the atmosphere of a planet outside our solar system in 2001. Sodium filters the alien star light of
HD 209458 as the hot Jupiter planet passes in front. The process and absorption spectrum are illustrated above. Image Credit: A. Feild,
STScI and
NASA website.
Absorption spectroscopy
Absorption spectroscopy
–
The infrared absorption spectrum of NASA laboratory
sulfur dioxide ice is compared with the infrared absorption spectra of ices on
Jupiter 's moon,
Io credit NASA, Bernard Schmitt, and
UKIRT.
Absorption spectroscopy
–
Absorption spectrum observed by the
Hubble Space Telescope
19.
Demantoid
–
Demantoid is the green gemstone variety of the mineral andradite, a member of the garnet group of minerals. Andradite is a calcium- and iron-rich garnet, the chemical formula is Ca3Fe23 with chromium substitution as the cause of the demantoid green color. Ferric iron is the cause of the yellow in the stone and it has the misnomers olivine, and Uralian emerald. In approximately 2003, reports began to circulate in the trade that some Russian demantoid garnets were being subjected to heat treatment in order to enhance their color. Such treatment is believed to be performed at low temperatures and is thought not to be detectable by gemological testing. Although garnets have been known since ancient times, the variety was not discovered until 1868 in Russias western central Ural Mountains. The find was an alluvial deposit about 110 kilometers from Ekaterinburg, north by northwest along the Bobrovka River, miners were immediately stunned by the highly refractive nature of the gem material, which is atypical for garnet. They began comparing it to diamond and referred to it as demantoid, from the French demant, the reason is obvious, with its high brilliance and dispersion. A second find was made 75 km. to the south of Ekaterinburg, on the Chusovaya, deposits are also found underground up to 3 meters deep in the demantoid placier. In all, there are five deposits of demantoid in this area, possessing an unusual green color and a dispersion greater than that of diamond, it quickly became a treasured and expensive gemstone. From the time of the find until about 1919, they were popular in Russia as the famous Peter Carl Fabergé made jewelry with them. In austere Communist Russia, these went out of style. More stones were found in the Bobrovka River in the 1970s and 1980s, around 1999, very limited production occurred in the central Ural Mountains. Many of the stones found then are for sale today, mining takes place along the rivers today, but some mining is still done secretively. A significant new find of demantoid and andradite took place in Namibia in 1996 at what is now dubbed the Green Dragon mine, in addition to the commercially-important deposits in Russia and Namibia, demantoids are also found in other some places, including Italy, Iran, and Afghanistan. Around 2009, there was a significant discovery of demantoid and andradite garnet in Madagascar, demantoid is the green variety of andradite garnet, so demantoids are always primarily green, but the exact shade ranges from a very strong yellowish green to nearly the color of a fine emerald. Some stones have a brownish cast, which is due to iron and its dispersion is unusually high, and this is often visible as fire, although in some cases the stones green body colour can render this effect less noticeable. Demantoid also has a refractive index of 1.80 to 1.89
Demantoid
–
Demantoid
20.
Chatoyancy
–
In gemology, chatoyancy, or chatoyance or cats eye effect, is an optical reflectance effect seen in certain gemstones. The precipitates that cause chatoyance in chrysoberyl are the mineral rutile, examined samples have yielded no evidence of tubes or fibres. The rutile precipitates all align perpendicularly with respect to cats eye effect and it is reasoned that the lattice parameter of the rutile matches only one of the three orthorhombic crystal axes of the chrysoberyl, resulting in preferred alignment along that direction. The effect can be likened to the sheen off a spool of silk, for a gemstone to show this effect best it must be cut en cabochon, with the fibers or fibrous structures parallel to the base of the finished gem. The best finished specimens show a sharply defined band of light that moves across the stone when it is rotated. Chatoyant stones of lesser quality display a banded effect as is typical with cats-eye varieties of quartz, faceted stones do not show the effect well. Glass optical cable can also display chatoyancy if properly cut, and has become a decorative material in a variety of vivid colors. The term cats eye, when used by itself as the name of a gemstone and it is also used as an adjective which indicates the chatoyance phenomenon in another stone, e. g. cats eye aquamarine. Figuring takes on a variety of forms and is referred to as flame, ribbon, tiger stripe and this effect is sometimes called wet look, since wetting wood with water often displays the chatoyancy, albeit only until the wood dries. Certain finishes cause the chatoyancy to become more pronounced, oil finishes, epoxy, and shellac can strongly bring out the wet look effect
Chatoyancy
–
Tiger's eye
Chatoyancy
Chatoyancy
–
Quartz cats-eye
21.
Silicate minerals
–
Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of rock-forming minerals and they are classified based on the structure of their silicate groups, which contain different ratios of silicon and oxygen. Nesosilicates, or orthosilicates, have the orthosilicate ion, which constitute isolated 4− tetrahedra that are connected only by interstitial cations and these exist as 3-member 6− and 6-member 12− rings, where T stands for a tetrahedrally coordinated cation. Inosilicates, or chain silicates, have interlocking chains of silicate tetrahedra with either SiO3,1,3 ratio, for single chains or Si4O11,4,11 ratio, for double chains. Nickel–Strunz classification,09. D Pyroxene group Enstatite – orthoferrosilite series Enstatite – MgSiO3 Ferrosilite – FeSiO3 Pigeonite – Ca0.251, all phyllosilicate minerals are hydrated, with either water or hydroxyl groups attached. Serpentine subgroup Antigorite – Mg3Si2O54 Chrysotile – Mg3Si2O54 Lizardite – Mg3Si2O54 Clay minerals group Halloysite – Al2Si2O54 Kaolinite – Al2Si2O54 Illite – 24O10 Montmorillonite –0 and this group comprises nearly 75% of the crust of the Earth. Tectosilicates, with the exception of the group, are aluminosilicates. Nickel–Strunz classification,09. F and 09. G,04. A, an introduction to the rock-forming minerals. Wise, W. S. Zussman, J. Rock-forming minerals, P.982 pp. Hurlbut, Cornelius S. Danas Manual of Mineralogy. Mindat. org, Dana classification Webmineral, Danas New Silicate Classification Media related to Silicates at Wikimedia Commons
Silicate minerals
–
Copper silicate mineral
chrysocolla
Silicate minerals
–
Nesosilicate specimens at the Museum of Geology in South Dakota
Silicate minerals
–
Kyanite crystals (unknown scale)
Silicate minerals
–
Sorosilicate exhibit at Museum of Geology in South Dakota
22.
Gemology
–
Gemology or gemmology is the science dealing with natural and artificial gemstone materials. It is considered a geoscience and a branch of mineralogy, some jewelers are academically trained gemologists and are qualified to identify and evaluate gems. This committee matured into the Gemmological Association of Great Britain, now an educational charity, the first US graduate of Gem-As Diploma Course, in 1929, was Robert Shipley, who later established both the Gemological Institute of America and the American Gem Society. There are now several schools and associations of gemologists and certification programs around the world. It is often difficult to obtain a judgement from a neutral laboratory. Analysis and estimation in the trade usually have to take place on site. Professional gemologists and gemstone buyers use mobile laboratories, which all necessary instruments in a travel case. Such so-called travel labs even have their own current supply, which makes them independent from infrastructure and they are also suitable for gemological expeditions. Gemstones are basically categorized based on their structure, specific gravity, refractive index. The physical property of hardness is defined by the non-linear Mohs scale of mineral hardness, gemologists study these factors while valuing or appraising cut and polished gemstones. The spectroscopic analysis of cut gemstones also allows a gemologist to understand the structure and identify its origin. For example, a ruby from Burma will have internal and optical activity variance from a Thai ruby. When the gemstones are in a state, the gemologist studies the external structure, the host rock and mineral association. Initially, the stone is identified by its color, refractive index, optical character, specific gravity, Gem identification is basically a process of elimination. Gemstones of similar color undergo non-destructive optical testing until there is one possible identity. Any single test is indicative, only, for example, the specific gravity of ruby is 4.00, glass is 3. 15–4.20, and cubic zirconia is 5. 6–5.9. So one can tell the difference between cubic zirconia and the other two, however, there is overlap between ruby and glass. And, as with all naturally occurring materials, no two gems are identical, one test to determine the gems identity is to measure the refraction of light in the gem
Gemology
–
A selection of gemstone pebbles made by tumbling rough rock with abrasive grit in a rotating drum. The biggest pebble here is 40 millimetres (1.6 in) long.
Gemology
–
Gemmological travel lab KA52KRS
Gemology
–
Traditional handheld refractometer
23.
Gemstone
–
A gemstone is a piece of mineral crystal which, in cut and polished form, is used to make jewelry or other adornments. However, certain rocks or organic materials that are not minerals are used for jewelry and are therefore often considered to be gemstones as well. Most gemstones are hard, but some soft minerals are used in jewelry because of their luster or other properties that have aesthetic value. Rarity is another characteristic that lends value to a gemstone, apart from jewelry, from earliest antiquity engraved gems and hardstone carvings, such as cups, were major luxury art forms. A gem maker is called a lapidary or gemcutter, a worker is a diamantaire. The carvings of Carl Fabergé are significant works in this tradition, the traditional classification in the West, which goes back to the ancient Greeks, begins with a distinction between precious and semi-precious, similar distinctions are made in other cultures. In modern usage the precious stones are diamond, ruby, sapphire, other stones are classified by their color, translucency and hardness. Another unscientific term for semi-precious gemstones used in art history and archaeology is hardstone, in modern times gemstones are identified by gemologists, who describe gems and their characteristics using technical terminology specific to the field of gemology. The first characteristic a gemologist uses to identify a gemstone is its chemical composition, for example, diamonds are made of carbon and rubies of aluminium oxide. Next, many gems are crystals which are classified by their crystal system such as cubic or trigonal or monoclinic, another term used is habit, the form the gem is usually found in. For example, diamonds, which have a crystal system, are often found as octahedrons. Gemstones are classified into different groups, species, and varieties, for example, ruby is the red variety of the species corundum, while any other color of corundum is considered sapphire. Other examples are the Emerald, aquamarine, red beryl, goshenite, heliodor, and morganite, gems are characterized in terms of refractive index, dispersion, specific gravity, hardness, cleavage, fracture, and luster. They may exhibit pleochroism or double refraction and they may have luminescence and a distinctive absorption spectrum. Material or flaws within a stone may be present as inclusions, gemstones may also be classified in terms of their water. This is a grading of the gems luster, transparency. Very transparent gems are considered first water, while second or third water gems are those of a lesser transparency, there is no universally accepted grading system for gemstones. Diamonds are graded using a system developed by the Gemological Institute of America in the early 1950s, historically, all gemstones were graded using the naked eye
Gemstone
–
A selection of gemstone pebbles made by tumbling rough rock with abrasive grit, in a rotating drum. The biggest pebble here is 40 mm long (1.6 inches).
Gemstone
–
Group of precious and semiprecious stones —both uncut and faceted— including (clockwise from top left)
diamond, uncut synthetic
sapphire,
ruby, uncut
emerald, and
amethyst crystal cluster.
Gemstone
–
Spanish emerald and gold pendant at
Victoria and Albert Museum
Gemstone
–
Enamelled gold, amethyst and pearl pendant, about 1880, Pasquale Novissimo (1844–1914), V&A Museum number M.36-1928
24.
Drammen
–
Drammen is a city in Buskerud, Norway. The port and river city of Drammen is centrally located in the eastern, Drammen is the capital of the county of Buskerud. There are more than 63000 inhabitants in the municipality, Drammen and the surrounding communities are growing more than ever before. The city makes good use of the river and inland waterway called Drammensfjord, no city in the country has received as many awards for environmental and urban development as Drammen,6 national and 2 international prizes since 2003. The Old Norse form of the name was Drafn. The fjord is, however, probably named after the river Drammenselva, the coat-of-arms is from modern times. They were granted on 17 November 1960, the arms are blue with a gray/silver column on top of a foundation of rocks. A key and a Viking sword are crossed in the forming a x. It is based upon the old seal dating from 1723 for Bragernes, the motto for Bragernes was In Fide Et Justitia Fortitudo, and the items in the seal are referring to this, key = faith, sword = justice, column on rocks = strength. The municipality of Drammen was established on 1 January 1838, the rural municipality of Skoger was merged with the municipality of Drammen on 1 January 1964 and was transferred from Vestfold county to Buskerud county at the same time. The city itself has 66000 inhabitants, making it Norways ninth largest, Drammen is currently divided into eight districts. The largest rock carving at Åskollen depicts a moose, Drammen originally consisted of three small seaports, Bragernes and Strømsø and Tangen. For trade purposes, small seaports were placed under market towns, despite their geographical proximity, Bragernes was placed under Christiania and Strømsø under Tønsberg. For this reason, cooperation between the adjacent seaport towns was almost impossible, in 1662, a merger was proposed to unite Strømsø and Bragernes to form a market town with the name Frederiksstrøm. The proposal was rejected by Frederick III of Denmark, Bragernes received limited market town rights in 1715, and merged with Strømsø to gain status as a single city on 19 June 1811. Its geographical location made the city favorable for seafaring, shipbuilding, log driving, during 19th century, paper and pulp industries were developed. Large parts of the city were ruined in the fire of 12–13 July 1866. The Drammen Line opened in 1872 providing rail service between Drammen and Oslo, in 1909, Drammen got the first trolleybus system in Scandinavia, the Drammen trolleybus
Drammen
–
Drammen kommune
Drammen
–
Map of the urban area of Drammen
Drammen
–
Map of Drammensfjorden
Drammen
–
Aass Brewery
25.
Buskerud
–
Buskerud is a county in Norway, bordering Akershus, Oslo, Oppland, Sogn og Fjordane, Hordaland, Telemark and Vestfold. The county extends from the Oslofjord and Drammensfjorden in the southeast to Hardangervidda mountain range in the northwest, the county administration is located in Drammen. The county is named after the old manor Buskerud located on the west side of the Drammen River in Åmot, the first element is the genitive case of biskup, bishop, the last element is ruð n clearing, farm. The farm was one of the largest in Buskerud, and the name of the farm was probably Modum. At the time of the Reformation the farm property of the Crown at which time the farm then served as the residence of the kings bailiffs until 1668. Buskerud extends from Hurum at the Oslofjord to the Halling mountains, the county is conventionally divided into traditional districts. These are Hallingdal, Numedal, Ringerike, Lower Buskerud, which was part of Vestfold. Hallingdal consists of Flå, Nes, Gol, Hemsedal, Ål, Numedal consists of Flesberg, Rollag and Nore og Uvdal. Ringerike consists of Hole, Krødsherad, Modum, Ringerike and Sigdal, Western Vingulmark consists of Hurum and Røyken. Lower Buskerud consists of Drammen, Hurum, Kongsberg, Lier, Nedre Eiker, Røyken, the district is merged from parts that belonged to Vestfold and Vingulmark. Buskeruds western part is a plateau with forested valleys and high, grassy pastures, its eastern part contains a lowland basin with many lakes. Tyrifjorden and Krøderen are the biggest lakes, numedalslågen, the third longest river in Norway, starting in Hordaland, runs through Buskerud unto Vestfold where it reaches the sea, while river Begna sweeps into lake Sperillen. Buskerud was separated from Akershus as an amt of its own in 1685 and it then consisted of the present districts Eiker, Hallingdal, and Ringerike. The area of the present municipalities of Flesberg, Hurum, Kongsberg, Lier, Nore og Uvdal, Rollag, the name Buskeruds amt was changed to Buskerud fylke in 1919. The municipality of Skoger was transferred from Vestfold to Buskerud in 1964, the area Ringerike may once have been a small kingdom. During the 10th century, Norways kings Olaf Tryggvason and Olaf Haraldsson grew up at Bønsnes in Ringerike, in the valley of Numedal, silver has been mined in Kongsberg from the 17th century until discontinued in 1957. Weapons industry had developed in Kongsberg from 1814, and various high tech industry companies now represent the towns major employers. At Modum there was also Blaafarveværket, a cobalt pigment production works, today, agriculture, lumber, wood-pulp mills and other related industries are the countys main economic activities, ample hydroelectric power is produced by the rivers Begna and Rands
Buskerud
–
Buskerud fylke
Buskerud
–
Map of Buskerud County
Buskerud
–
Winter in
Blefjell
Buskerud
–
This article may be expanded with text translated from the corresponding article in Norwegian. (July 2012) Click [show] for important translation instructions.
26.
Norway
–
The Antarctic Peter I Island and the sub-Antarctic Bouvet Island are dependent territories and thus not considered part of the Kingdom. Norway also lays claim to a section of Antarctica known as Queen Maud Land, until 1814, the kingdom included the Faroe Islands, Greenland, and Iceland. It also included Isle of Man until 1266, Shetland and Orkney until 1468, Norway has a total area of 385,252 square kilometres and a population of 5,258,317. The country shares a long border with Sweden. Norway is bordered by Finland and Russia to the north-east, Norway has an extensive coastline, facing the North Atlantic Ocean and the Barents Sea. King Harald V of the Dano-German House of Glücksburg is the current King of Norway, erna Solberg became Prime Minister in 2013, replacing Jens Stoltenberg. A constitutional monarchy, Norway divides state power between the Parliament, the Cabinet and the Supreme Court, as determined by the 1814 Constitution, the kingdom is established as a merger of several petty kingdoms. By the traditional count from the year 872, the kingdom has existed continuously for 1,144 years, Norway has both administrative and political subdivisions on two levels, counties and municipalities. The Sámi people have an amount of self-determination and influence over traditional territories through the Sámi Parliament. Norway maintains close ties with the European Union and the United States, the country maintains a combination of market economy and a Nordic welfare model with universal health care and a comprehensive social security system. Norway has extensive reserves of petroleum, natural gas, minerals, lumber, seafood, the petroleum industry accounts for around a quarter of the countrys gross domestic product. On a per-capita basis, Norway is the worlds largest producer of oil, the country has the fourth-highest per capita income in the world on the World Bank and IMF lists. On the CIAs GDP per capita list which includes territories and some regions, from 2001 to 2006, and then again from 2009 to 2017, Norway had the highest Human Development Index ranking in the world. It also has the highest inequality-adjusted ranking, Norway ranks first on the World Happiness Report, the OECD Better Life Index, the Index of Public Integrity and the Democracy Index. Norway has two names, Noreg in Nynorsk and Norge in Bokmål. The name Norway comes from the Old English word Norðrveg mentioned in 880, meaning way or way leading to the north. In contrasting with suðrvegar southern way for Germany, and austrvegr eastern way for the Baltic, the Anglo-Saxon of Britain also referred to the kingdom of Norway in 880 as Norðmanna land. This was the area of Harald Fairhair, the first king of Norway, and because of him
Norway
–
The
helmet found at Gjermundbu near
Haugsbygd,
Buskerud, is the only
Viking Age helmet that has been found.
Norway
–
Flag
Norway
–
The
Gokstad ship at the
Viking Ship Museum in
Oslo, Norway
Norway
–
The
Battle of the Sound between an allied Dano-Norwegian–
Dutch fleet and the Swedish navy, 8 November 1658 (29 October
O.S.)
27.
Brazil
–
Brazil, officially the Federative Republic of Brazil, is the largest country in both South America and Latin America. As the worlds fifth-largest country by area and population, it is the largest country to have Portuguese as an official language. Its Amazon River basin includes a vast tropical forest, home to wildlife, a variety of ecological systems. This unique environmental heritage makes Brazil one of 17 megadiverse countries, Brazil was inhabited by numerous tribal nations prior to the landing in 1500 of explorer Pedro Álvares Cabral, who claimed the area for the Portuguese Empire. Brazil remained a Portuguese colony until 1808, when the capital of the empire was transferred from Lisbon to Rio de Janeiro, in 1815, the colony was elevated to the rank of kingdom upon the formation of the United Kingdom of Portugal, Brazil and the Algarves. Independence was achieved in 1822 with the creation of the Empire of Brazil, a state governed under a constitutional monarchy. The ratification of the first constitution in 1824 led to the formation of a bicameral legislature, the country became a presidential republic in 1889 following a military coup détat. An authoritarian military junta came to power in 1964 and ruled until 1985, Brazils current constitution, formulated in 1988, defines it as a democratic federal republic. The federation is composed of the union of the Federal District, the 26 states, Brazils economy is the worlds ninth-largest by nominal GDP and seventh-largest by GDP as of 2015. A member of the BRICS group, Brazil until 2010 had one of the worlds fastest growing economies, with its economic reforms giving the country new international recognition. Brazils national development bank plays an important role for the economic growth. Brazil is a member of the United Nations, the G20, BRICS, Unasul, Mercosul, Organization of American States, Organization of Ibero-American States, CPLP. Brazil is a power in Latin America and a middle power in international affairs. One of the worlds major breadbaskets, Brazil has been the largest producer of coffee for the last 150 years and it is likely that the word Brazil comes from the Portuguese word for brazilwood, a tree that once grew plentifully along the Brazilian coast. In Portuguese, brazilwood is called pau-brasil, with the word brasil commonly given the etymology red like an ember, formed from Latin brasa and the suffix -il. As brazilwood produces a red dye, it was highly valued by the European cloth industry and was the earliest commercially exploited product from Brazil. The popular appellation eclipsed and eventually supplanted the official Portuguese name, early sailors sometimes also called it the Land of Parrots. In the Guarani language, a language of Paraguay, Brazil is called Pindorama
Brazil
–
Megaliths in the
Solstice Archaeological Park, in
Amapá, erected between 500 and 2000 years ago, probably to carry out
astronomical observations.
Brazil
–
Flag
Brazil
–
Representation of the landing of
Pedro Álvares Cabral in
Porto Seguro, 1500.
Brazil
–
Painting showing the arrest of
Tiradentes; he was sentenced to death for his involvement in the best known
movement for independence in Colonial Brazil.
28.
Skarn
–
Skarns or tactites are calcium-bearing calc–silicate rocks. Skarns are most often formed at the zone between intrusions of granitic magma bodies and carbonate sedimentary rocks such as limestone and dolostone. Hot fluids derived from the magma are rich in silica, iron, aluminium. These fluids mix in the zone, dissolve calcium-rich carbonate rocks. The resulting metamorphic rock may consist of a wide variety of minerals dependent largely on the original composition of the magmatic fluids. Skarns are sometimes associated with mineable accumulations of metallic ores of iron, copper, zinc, lead, gold, in such cases these deposits are called skarn deposits. Skarns are, in their broadest sense, formed by mass and chemical transport and they need not be igneous in origin, two adjacent sedimentary layers such as a banded iron formation and a limestone may react to exchange metals and fluids during metamorphism, creating a skarn. However, the widest use of the word is in describing the metasomatised zones of wall adjacent to granites. Skarns which are created by reaction between metamorphic-sedimentary layers are known as chemical skarns or skarnoids. Skarns must also be distinguished from calc-silicate hornfels, usually by field relationships, skarns of igneous origin are classified as exoskarns or endoskarns. Exoskarns occur at and outside the granite which produced them, and are alterations of wall rocks, typical skarn minerals include pyroxene, garnet, idocrase, wollastonite, actinolite, magnetite or hematite, and epidote. Often, feldspathoids and rare calc-silicates such as scapolite are found in marginal areas. Skarns are a class of rocks and are intimately associated with granite intrusions. Skarns are rarely seen with other types of granites, because of the fluid chemistry, s-type granites are more prone to generating late-stage fluid rich in silica, incompatible elements and halides because they are generally more potassic, oxidised and hydrous. Exoskarns are formed when fluids left over from the crystallisation of the granite are ejected from the mass at the stages of emplacement. When these fluids come into contact with rocks, usually carbonates such as limestone or dolostone. Because these fluids carry dissolved silica, iron, metals, halides and sulfur, uncommon types of skarns are formed in contact with sulfidic or carbonaceous rocks such as black shales, graphite shales, banded iron formations and, occasionally, salt or evaporites. Here, fluids react less via chemical exchange of ions, endoskarns are rarer, generally because the fluids created by a granite are usually formed in equilibrium with the minerals of the granite
Skarn
–
Microscopic view of skarn under crossed polarizers
Skarn
–
Hand sample of skarn containing
serpentinite from the edge of the Alta Stock,
Little Cottonwood Canyon, Utah
29.
Contact metamorphism
–
Metamorphism is the change of minerals or geologic texture in pre-existing rocks, without the protolith melting into liquid magma. The change occurs primarily due to heat, pressure, and the introduction of chemically active fluids, the chemical components and crystal structures of the minerals making up the rock may change even though the rock remains a solid. Changes at or just beneath Earths surface due to weathering and/or diagenesis are not classified as metamorphism, Metamorphism typically occurs between diagenesis, and melting. Three types of metamorphism exist, contact, dynamic, and regional, Metamorphism produced with increasing pressure and temperature conditions is known as prograde metamorphism. Conversely, decreasing temperatures and pressure characterize retrograde metamorphism, Metamorphic rocks can change without melting. When pressure is applied, somewhat flattened grains that orient in the same direction have a stable configuration. The upper boundary of metamorphic conditions is related to the onset of melting processes in the rock, the maximum temperature for metamorphism is typically 700 –900 °C, depending on the pressure and on the composition of the rock. Migmatites are rocks formed at this limit, which contain pods. Since the 1980s it has recognized that rocks are rarely dry enough. Conditions producing widespread regionally metamorphosed rocks occur during an orogenic event, the collision of two continental plates or island arcs with continental plates produce the extreme compressional forces required for the metamorphic changes typical of regional metamorphism. These orogenic mountains are eroded, exposing the intensely deformed rocks typical of their cores. The conditions within the slab as it plunges toward the mantle in a subduction zone also produce regional metamorphic effects. The techniques of structural geology are used to unravel the collisional history, regional metamorphism can be described and classified into metamorphic facies or metamorphic zones of temperature/pressure conditions throughout the orogenic terrane. Contact metamorphism occurs typically around intrusive igneous rocks as a result of the increase caused by the intrusion of magma into cooler country rock. The area surrounding the intrusion where the contact metamorphism effects are present is called the metamorphic aureole, contact metamorphic rocks are usually known as hornfels. Rocks formed by contact metamorphism may not present signs of deformation and are often fine-grained. Contact metamorphism is greater adjacent to the intrusion and dissipates with distance from the contact, the size of the aureole depends on the heat of the intrusion, its size, and the temperature difference with the wall rocks. Dikes generally have small aureoles with minimal metamorphism whereas large ultramafic intrusions can have significantly thick, the metamorphic grade of an aureole is measured by the peak metamorphic mineral which forms in the aureole
Contact metamorphism
–
A metamorphic aureole in the Henry Mountains, Utah. The greyish rock on top is the igneous intrusion, consisting of porphyritic granodiorite from the
Henry Mountains laccolith, and the pinkish rock on the bottom is the sedimentary country rock, a siltstone. In between, the metamorphosed siltstone is visible as both the dark layer (~5cm thick) and the pale layer below it.
Contact metamorphism
–
Schematic representation of a metamorphic reaction. Abbreviations of minerals: act =
actinolite; chl =
chlorite; ep =
epidote; gt =
garnet; hbl =
hornblende; plag =
plagioclase. Two minerals represented in the figure do not participate in the reaction, they can be
quartz and
K-feldspar. This reaction takes place in nature when a rock goes from
amphibolite facies to
greenschist facies.
Contact metamorphism
–
Metamorphic Facies with regard to temperature and pressure
30.
Limestone
–
Limestone is a sedimentary rock, composed mainly of skeletal fragments of marine organisms such as coral, forams and molluscs. Its major materials are the minerals calcite and aragonite, which are different crystal forms of calcium carbonate, about 10% of sedimentary rocks are limestones. The solubility of limestone in water and weak acid solutions leads to karst landscapes, most cave systems are through limestone bedrock. The first geologist to distinguish limestone from dolomite was Belsazar Hacquet in 1778, like most other sedimentary rocks, most limestone is composed of grains. Most grains in limestone are skeletal fragments of organisms such as coral or foraminifera. Other carbonate grains comprising limestones are ooids, peloids, intraclasts and these organisms secrete shells made of aragonite or calcite, and leave these shells behind when they die. Limestone often contains variable amounts of silica in the form of chert or siliceous skeletal fragment, some limestones do not consist of grains at all, and are formed completely by the chemical precipitation of calcite or aragonite, i. e. travertine. Secondary calcite may be deposited by supersaturated meteoric waters and this produces speleothems, such as stalagmites and stalactites. Another form taken by calcite is oolitic limestone, which can be recognized by its granular appearance, the primary source of the calcite in limestone is most commonly marine organisms. Some of these organisms can construct mounds of rock known as reefs, below about 3,000 meters, water pressure and temperature conditions cause the dissolution of calcite to increase nonlinearly, so limestone typically does not form in deeper waters. Limestones may also form in lacustrine and evaporite depositional environments, calcite can be dissolved or precipitated by groundwater, depending on several factors, including the water temperature, pH, and dissolved ion concentrations. Calcite exhibits a characteristic called retrograde solubility, in which it becomes less soluble in water as the temperature increases. Impurities will cause limestones to exhibit different colors, especially with weathered surfaces, Limestone may be crystalline, clastic, granular, or massive, depending on the method of formation. Crystals of calcite, quartz, dolomite or barite may line small cavities in the rock, when conditions are right for precipitation, calcite forms mineral coatings that cement the existing rock grains together, or it can fill fractures. Travertine is a banded, compact variety of limestone formed along streams, particularly there are waterfalls. Calcium carbonate is deposited where evaporation of the leaves a solution supersaturated with the chemical constituents of calcite. Tufa, a porous or cellular variety of travertine, is found near waterfalls, coquina is a poorly consolidated limestone composed of pieces of coral or shells. During regional metamorphism that occurs during the building process, limestone recrystallizes into marble
Limestone
–
Limestone outcrop in the
Torcal de Antequera nature reserve of
Málaga, Spain
Limestone
–
Limestone quarry at
Cedar Creek, Virginia, USA
Limestone
–
Cutting the limestone blocks at a quarry in
Gozo,
Malta
Limestone
–
Limestone as building material
31.
Igneous rock
–
Igneous rock, or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or lava, the magma can be derived from partial melts of existing rocks in either a planets mantle or crust. Typically, the melting is caused by one or more of three processes, an increase in temperature, a decrease in pressure, or a change in composition, solidification into rock occurs either below the surface as intrusive rocks or on the surface as extrusive rocks. Igneous rock may form with crystallization to form granular, crystalline rocks, Igneous and metamorphic rocks make up 90–95% of the top 16 km of the Earths crust by volume. Igneous rocks form about 15% of the Earths current land surface, most of the Earths oceanic crust is made of igneous rock. In terms of modes of occurrence, igneous rocks can be either intrusive or extrusive, the mineral grains in such rocks can generally be identified with the naked eye. Intrusive rocks can also be classified according to the shape and size of the intrusive body, typical intrusive formations are batholiths, stocks, laccoliths, sills and dikes. When the magma solidifies within the earths crust, it cools slowly forming coarse textured rocks, such as granite, gabbro, the central cores of major mountain ranges consist of intrusive igneous rocks, usually granite. When exposed by erosion, these cores may occupy huge areas of the Earths surface, intrusive igneous rocks that form at depth within the crust are termed plutonic rocks and are usually coarse-grained. Intrusive igneous rocks that form near the surface are termed subvolcanic or hypabyssal rocks, hypabyssal rocks are less common than plutonic or volcanic rocks and often form dikes, sills, laccoliths, lopoliths, or phacoliths. Extrusive igneous rocks, also known as rocks, are formed at the crusts surface as a result of the partial melting of rocks within the mantle. Extrusive igneous rocks cool and solidify quicker than intrusive igneous rocks and they are formed by the cooling of molten magma on the earths surface. The magma, which is brought to the surface through fissures or volcanic eruptions, hence such rocks are smooth, crystalline and fine-grained. Basalt is an extrusive igneous rock and forms lava flows, lava sheets. Some kinds of basalt solidify to form long polygonal columns, the Giants Causeway in Antrim, Northern Ireland is an example. The molten rock, with or without suspended crystals and gas bubbles, is called magma and it rises because it is less dense than the rock from which it was created. When magma reaches the surface from beneath water or air, it is called lava, eruptions of volcanoes into air are termed subaerial, whereas those occurring underneath the ocean are termed submarine. Black smokers and mid-ocean ridge basalt are examples of volcanic activity
Igneous rock
–
Shield
Igneous rock
–
Forming of igneous rock
Igneous rock
–
Close-up of granite (an intrusive igneous rock) exposed in
Chennai, India.
Igneous rock
–
Extrusive igneous rock is made from lava released by volcanoes
32.
Schist
–
Schist is a medium-grade metamorphic rock with medium to large, flat, sheet-like grains in a preferred orientation. It is defined by having more than 50% platy and elongated minerals, often finely interleaved with quartz and these lamellar minerals include micas, chlorite, talc, hornblende, graphite, and others. Quartz often occurs in drawn-out grains to such an extent that a form called quartz schist is produced. Schist forms at a temperature and has larger grains than phyllite. Geological foliation with medium to large grained flakes in a preferred orientation is called schistosity. The names of various schists are derived from their mineral constituents, for example, schists rich in mica are called mica schists and include biotite or muscovite. Most schists are mica schists, but graphite and chlorite schists are also common, Schists are also named for their prominent or perhaps unusual mineral constituents, as in the case of garnet schist, tourmaline schist, and glaucophane schist. The individual mineral grains in schist, drawn out into flaky scales by heat and pressure, Schist is characteristically foliated, meaning that the individual mineral grains split off easily into flakes or slabs. Most schists are derived from clays and muds that have passed through a series of processes involving the production of shales, slates and phyllites as intermediate steps. Certain schists are derived from fine-grained igneous rocks such as basalts, before the mid-18th century, the terms slate, shale and schist were not sharply differentiated by those involved with mining. In the context of underground mining, shale was frequently referred to as slate well into the 20th century. During metamorphism, rocks which were originally sedimentary, igneous or metamorphic are converted into schists, if the composition of the rocks was originally similar, they may be very difficult to distinguish from one another if the metamorphism has been great. A quartz-porphyry, for example, and a fine grained feldspathic sandstone, usually, however, it is possible to distinguish between sedimentary and igneous schists and gneisses. If, for example, the district occupied by these rocks has traces of bedding, clastic structure, or unconformability. In other cases intrusive junctions, chilled edges, contact alteration or porphyritic structure may prove that in its original condition a metamorphic gneiss was an igneous rock. Such rocks as limestones, dolomites, quartzites and aluminous shales have very definite chemical characteristics which distinguish them even when completely recrystallized, the schists are classified principally according to the minerals they consist of and on their chemical composition. For example, many metamorphic limestones, marbles, and calc-schists, with crystalline dolomites, contain silicate minerals such as mica, tremolite, diopside, scapolite, quartz and they are derived from calcareous sediments of different degrees of purity. Another group is rich in quartz, with amounts of white and black mica, garnet, feldspar, zoisite
Schist
–
Schist specimen showing the characteristic "scaly" schistose texture, caused by platy micas
Schist
–
Microscopic view of garnet-mica-schist in
thin section under polarized light with a large garnet crystal (black) in a matrix of quartz and feldspar (white and gray grains) and parallel strands of mica (red, purple and brown).
Schist
–
View of cut garnet-mica-schist
Schist
–
Manhattan schist from southeastern New York State
33.
Serpentinite
–
Serpentinite is a rock composed of one or more serpentine group minerals. Minerals in this group are formed by serpentinization, a hydration, the mineral alteration is particularly important at the sea floor at tectonic plate boundaries. Serpentinization is a geological low-temperature metamorphic process involving heat and water in which low-silica mafic and ultramafic rocks are oxidized and hydrolyzed with water into serpentinite. Peridotite, including dunite, at and near the seafloor and in mountain belts is converted to serpentine, brucite, magnetite, and other minerals — some rare, such as awaruite, and even native iron. In the process large amounts of water are absorbed into the increasing the volume. The density changes from 3.3 to 2.7 g/cm3 with a concurrent volume increase on the order of 30-40%, the reaction is highly exothermic and rock temperatures can be raised by about 260 °C, providing an energy source for formation of non-volcanic hydrothermal vents. The magnetite-forming chemical reactions produce hydrogen gas under anaerobic conditions prevailing deep in the mantle, carbonates and sulfates are subsequently reduced by hydrogen and form methane and hydrogen sulfide. The hydrogen, methane, and hydrogen sulfide provide energy sources for deep sea chemotroph microorganisms, serpentinite is formed from olivine via several reactions, some of which are complementary. Olivine is a solution between the magnesium-endmember forsterite and the iron-endmember fayalite. Serpentinite reaction 1a and 1b, below, exchange silica between forsterite and fayalite to form serpentine group minerals and magnetite, Reaction 1c describes the hydration of olivine with water only to yield serpentine and Mg2. Talc and magnesian chlorite are possible products, together with the serpentine minerals antigorite, lizardite, the final mineralogy depends both on rock and fluid compositions, temperature, and pressure. Antigorite forms in reactions at temperatures that can exceed 600 °C during metamorphism, lizardite and chrysotile can form at low temperatures very near the Earths surface. In the presence of carbon dioxide, however, serpentinitization may form either magnesite or generate methane and it is thought that some hydrocarbon gases may be produced by serpentinite reactions within the oceanic crust. Or, in balanced form, Reaction 2a is favored if the serpentinite is Mg-poor or if there isnt enough carbon dioxide to promote talc formation, Reaction 2b is favored in highly magnesian compositions and low partial pressure of carbon dioxide. If an olivine composition contains sufficient fayalite, then olivine plus water can completely metamorphose to serpentine, serpentinitization of a mass of peridotite usually destroys all previous textural evidence because the serpentine minerals are weak and behave in a very ductile fashion. Serpentine is the product of the reaction between water and fayalites ferrous ions, the process is effected by bacteria under anaerobic conditions. The two unoxidised ferrous ions still available in the three units of fayalite finally combine with the four ferric cations and oxide anions to form two formula units of magnetite. Serpentinization has been proposed as an alternative source for the observed methane traces
Serpentinite
–
A sample of serpentinite rock, partially made up of
chrysotile, from Slovakia
Serpentinite
–
Sample of serpentinite from the
Golden Gate National Recreation Area, California, USA
Serpentinite
–
Chromitic serpentinite (7.9 cm across),
Styria Province, Austria.
Protolith was a Proterozoic-Early Paleozoic upper mantle
dunite peridotite that has been multiply metamorphosed during the Devonian, Permian, and Mesozoic.
Serpentinite
–
Tightly folded serpentinite from the
Tux Alps, Austria. Closeup view about 30cm × 20cm.
34.
Titanium
–
Titanium is a chemical element with symbol Ti and atomic number 22. It is a transition metal with a silver color, low density. Titanium is resistant to corrosion in sea water, aqua regia, titanium was discovered in Cornwall, Great Britain, by William Gregor in 1791, and it is named by Martin Heinrich Klaproth for the Titans of Greek mythology. The metal is extracted from its principal mineral ores by the Kroll, the most common compound, titanium dioxide, is a popular photocatalyst and is used in the manufacture of white pigments. Other compounds include titanium tetrachloride, a component of smoke screens and catalysts, and titanium trichloride, the two most useful properties of the metal are corrosion resistance and strength-to-density ratio, the highest of any metallic element. In its unalloyed condition, titanium is as strong as some steels, there are two allotropic forms and five naturally occurring isotopes of this element, 46Ti through 50Ti, with 48Ti being the most abundant. Although they have the number of valence electrons and are in the same group in the periodic table. As a metal, titanium is recognized for its high strength-to-weight ratio and it is a strong metal with low density that is quite ductile, lustrous, and metallic-white in color. The relatively high melting point makes it useful as a refractory metal and it is paramagnetic and has fairly low electrical and thermal conductivity. Commercial grades of titanium have ultimate tensile strength of about 434 MPa, equal to that of common, low-grade steel alloys, titanium is 60% denser than aluminium, but more than twice as strong as the most commonly used 6061-T6 aluminium alloy. Certain titanium alloys achieve tensile strengths of over 1400 MPa, however, titanium loses strength when heated above 430 °C. Titanium is not as hard as some grades of heat-treated steel, it is non-magnetic, machining requires precautions, because the material might gall unless sharp tools and proper cooling methods are used. Like steel structures, those made from titanium have a limit that guarantees longevity in some applications. The metal is an allotrope of an hexagonal α form that changes into a body-centered cubic β form at 882 °C. The specific heat of the α form increases dramatically as it is heated to this transition temperature but then falls, similar to zirconium and hafnium, an additional omega phase exists, which is thermodynamically stable at high pressures, but metastable at ambient pressures. This phase is usually hexagonal or trigonal and can be considered to be due to a soft longitudinal acoustic phonon of the β phase causing collapse of planes of atoms, like aluminium and magnesium, titanium metal and its alloys oxidize immediately upon exposure to air. Titanium readily reacts with oxygen at 1,200 °C in air and it is, however, slow to react with water and air at ambient temperatures because it forms a passive oxide coating that protects the bulk metal from further oxidation. When it first forms, this layer is only 1–2 nm thick but continues to grow slowly
Titanium
–
Titanium, 22 Ti
Titanium
–
Titanium(III) compounds are characteristically violet, illustrated by this aqueous solution of
titanium trichloride.
Titanium
–
Martin Heinrich Klaproth named titanium for the
Titans of
Greek mythology.
Titanium
–
Titanium sponge, made by the
Kroll process
35.
Vesuvianite
–
Vesuvianite, also known as idocrase, is a green, brown, yellow, or blue silicate mineral. Vesuvianite occurs as crystals in skarn deposits and limestones that have been subjected to contact metamorphism. It was first discovered within included blocks or adjacent to lavas on Mount Vesuvius, attractive-looking crystals are sometimes cut as gemstones. Localities which have yielded fine crystallized specimens include Mount Vesuvius and the Ala Valley near Turin, the specific gravity is 3.4 and the hardness 6 1⁄2. The name vesuvianite was given by A. G. Werner in 1795, because crystals of the mineral are found at Vesuvius. Several other names have applied to this species, one of which. A sky bluish variety known as cyprine and as has been reported from Franklin, New Jersey and other locations, californite is a name sometimes used for jade-like vesuvianite, also known as California jade, American jade or Vesuvianite jade. Xanthite is a rich variety. Wiluite is an optically positive variety from Wilui, Siberia, idocrase is an older synonym sometimes used for gemstone-quality vesuvianite
Vesuvianite
–
Vesuvianite from the Jeffrey Mine in
Asbestos, Quebec
Vesuvianite
–
Tumbled vesuvianite pebble
36.
Chlorite group
–
The chlorites are a group of phyllosilicate minerals. Chlorites can be described by the following four endmembers based on their chemistry via substitution of the four elements in the silicate lattice, Mg, Fe, Ni. Clinochlore, O108 Chamosite, O108 Nimite, O108 Pennantite, 64O108 In addition, zinc, lithium, the great range in composition results in considerable variation in physical, optical, and X-ray properties. Similarly, the range of chemical composition allows chlorite group minerals to exist over a range of temperature and pressure conditions. For this reason chlorite minerals are ubiquitous minerals within low and medium temperature metamorphic rocks, some rocks, hydrothermal rocks. The name chlorite is from the Greek chloros, meaning green, the typical general formula is, 34O102·36. This formula emphasizes the structure of the group, chlorites have a 2,1 sandwich structure, this is often referred to as a talc layer. Unlike other 2,1 clay minerals, a chlorites interlayer space is composed of 6 and this 6 unit is more commonly referred to as the brucite-like layer, due to its closer resemblance to the mineral brucite. Therefore, chlorites structure appears as follows, -t-o-t-brucite-t-o-t-brucite, thats why they are also called 2,1,1 minerals. An older classification divided the chlorites into two subgroups, the orthochlorites and leptochlorites, the terms are seldom used and the ortho prefix is somewhat misleading as the chlorite crystal system is monoclinic and not orthorhombic. Chlorite is commonly found in rocks as an alteration product of mafic minerals such as pyroxene, amphibole. Chlorite is a common mineral associated with ore deposits and commonly occurs with epidote, sericite, adularia. Chlorite is also a metamorphic mineral, usually indicative of low-grade metamorphism. It is the species of the zeolite facies and of lower greenschist facies. It occurs in the quartz, albite, sericite, chlorite, within ultramafic rocks, metamorphism can also produce predominantly clinochlore chlorite in association with talc. Chlorite occurs naturally in a variety of locations and forms, for example, chlorite is found naturally in certain parts of Wales in mineral schists. Chlorite is found in large boulders scattered on the surface on Ring Mountain in Marin County. Clinoclore, pennantite, and chamosite are the most common varieties, several other sub-varieties have been described
Chlorite group
–
Chlorite group
Chlorite group
–
Quartz crystal with chlorite inclusions from
Minas Gerais,
Brazil (size: 4.2 × 3.9 × 3.3 cm)
Chlorite group
–
Chlorite
pseudomorph after
garnet from Michigan (size: 3.5 × 3.1 × 2.7 cm)
Chlorite group
–
Chlorite schist
37.
Epidote
–
Epidote is a calcium aluminium iron sorosilicate mineral. The faces are often deeply striated and crystals are often twinned, many of the characters of the mineral vary with the amount of iron present for instance, the color, the optical constants, and the specific gravity. The color is green, grey, brown or nearly black and it displays strong pleochroism, the pleochroic colors being usually green, yellow and brown. Clinozoisite is green, white or pale rose-red group species containing very little iron, the name, due to Haüy, is derived from the Greek word epidosis which means addition in allusion to one side of the ideal prism being longer than the other. Epidote is an abundant rock-forming mineral, but one of secondary origin and it occurs in marble and schistose rocks of metamorphic origin. It is also a product of alteration of various minerals composing igneous rocks. A rock composed of quartz and epidote is known as epidosite, the perfectly transparent, dark green crystals from the Knappenwand and from Brazil have occasionally been cut as gemstones. Belonging to the same group with epidote are the species piemontite and allanite. Piemontite occurs as small, reddish-black, monoclinic crystals in the mines at San Marcel, near Ivrea in Piedmont. The purple color of the Egyptian porfido rosso antico is due to the presence of this mineral, allanite and dollaseite- have the same general epidote formula and contain metals of the cerium group. The crystallographic and optical characters are similar to those of epidote, the pleochroism is strong with reddish-, yellowish-, and greenish-brown colors. Although not a mineral, allanite is of fairly wide distribution as a primary accessory constituent of many crystalline rocks, gneiss, granite, syenite, rhyolite, andesite. It was first found in the granite of east Greenland and described by Thomas Allan in 1808, allanite is a mineral readily altered by hydration, becoming optically isotropic and amorphous, for this reason several varieties have been distinguished, and many different names applied. Orthite was the name given by Jöns Berzelius in 1818 to a form found as slender prismatic crystals, sometimes a foot in length, at Finbo. Dollaseite is less common, famous from the Ostanmossa mine in the Norberg district of Sweden, dallasite This article incorporates text from a publication now in the public domain, Chisholm, Hugh, ed. article name needed
Epidote
–
Epidote crystals – Deposit topotype
Epidote
–
Epidote from
Alaska
Epidote
–
Sample of dollaseite (dark brown matrix at arrow points) from Sweden
38.
Spinel
–
Spinel is the magnesium aluminium member of the larger spinel group of minerals. It has the formula MgAl2O4 in the crystal system. Its name comes from Latin spina, balas ruby is an old name for a rose-tinted variety of spinel. Spinel crystallizes in the system, common crystal forms are octahedra. It has an imperfect cleavage and a conchoidal fracture. Its hardness is 8, its gravity is 3. 5–4.1. It may be colorless, but is usually shades of red, blue, green, yellow, brown, black. There is a natural white spinel, now lost, that surfaced briefly in what is now Sri Lanka. The Samarian Spinel is the largest known spinel in the world, the transparent red spinels were called spinel-rubies or balas rubies. In the past, before the arrival of modern science, spinels, after the 18th century the word ruby was only used for the red gem variety of the mineral corundum and the word spinel came to be used. Balas is derived from Balascia, the ancient name for Badakhshan, mines in the Gorno Badakhshan region of Tajikistan was for centuries the main source for red and pink spinels. Spinel has long been found in the gravel of Sri Lanka and in limestones of the Badakshan Province in modern-day Afghanistan and Tajikistan. Recently gem quality spinels also found in the marbles of Luc Yen, Mahenge and Matombo, Tsavo and in the gravels of Tunduru and this is why spinel and ruby are often found together. Spinel, 2O4, is common in peridotite in the uppermost Earths mantle, Spinel, Al2O4, is a common mineral in the Ca-Al-rich inclusions in some chondritic meteorites. Synthetic spinel, accidentally produced in the middle of the 18th century, has described more recently in scientific publications in 2000 and 2004. By 2015, transparent spinel was being made in sheets and other shapes through sintering, synthetic spinel which looks like glass but has notably higher strength against pressure, can also have applications in military and commercial use. Spinel group Ceylonite The Samarian Spinel, the largest known spinel in the world, part of the Iranian Crown Jewels Black Princes Ruby Deer, Howie, an Introduction to the Rock-Forming Minerals, Longman, pp. 424–433, ISBN 0-582-44210-9. Gemstones of the World 3rd edition, Sterling, pp. 116–117, Spinel structure at the University of Wisconsin - Green Bay Spinel structure at the Institut for materials science of the University of Kiel Value of Spinel
Spinel
–
Spinel: 1.83 and 4.13
ct
Spinel
–
Cut spinel
39.
Calcite
–
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate. The Mohs scale of hardness, based on scratch hardness comparison. Other polymorphs of calcium carbonate are the minerals aragonite and vaterite, aragonite will change to calcite at 380–470 °C, and vaterite is even less stable. Calcite is derived from the German Calcit, a term coined in the 19th century from the Latin word for lime and it is thus etymologically related to chalk. Calcite crystals are trigonal-rhombohedral, though actual calcite rhombohedra are rare as natural crystals, however, they show a remarkable variety of habits including acute to obtuse rhombohedra, tabular forms, prisms, or various scalenohedra. Calcite exhibits several twinning types adding to the variety of observed forms and it may occur as fibrous, granular, lamellar, or compact. Cleavage is usually in three directions parallel to the rhombohedron form and its fracture is conchoidal, but difficult to obtain. It has a defining Mohs hardness of 3, a gravity of 2.71. Color is white or none, though shades of gray, red, orange, yellow, green, blue, violet, brown, calcite is transparent to opaque and may occasionally show phosphorescence or fluorescence. A transparent variety called Iceland spar is used for optical purposes, acute scalenohedral crystals are sometimes referred to as dogtooth spar while the rhombohedral form is sometimes referred to as nailhead spar. Single calcite crystals display an optical property called birefringence and this strong birefringence causes objects viewed through a clear piece of calcite to appear doubled. The birefringent effect was first described by the Danish scientist Rasmus Bartholin in 1669, at a wavelength of ~590 nm calcite has ordinary and extraordinary refractive indices of 1.658 and 1.486, respectively. Between 190 and 1700 nm, the refractive index varies roughly between 1.9 and 1.5, while the extraordinary refractive index varies between 1.6 and 1.4. Calcite, like most carbonates, will dissolve with most forms of acid, calcite can be either dissolved by groundwater or precipitated by groundwater, depending on several factors including the water temperature, pH, and dissolved ion concentrations. Although calcite is fairly insoluble in water, acidity can cause dissolution of calcite. Ambient carbon dioxide, due to its acidity, has a slight solubilizing effect on calcite, calcite exhibits an unusual characteristic called retrograde solubility in which it becomes less soluble in water as the temperature increases. When conditions are right for precipitation, calcite forms mineral coatings that cement the existing rock grains together or it can fill fractures. On a landscape scale, continued dissolution of calcium carbonate-rich rocks can lead to the expansion and eventual collapse of cave systems, high-grade optical calcite was used in World War II for gun sights, specifically in bomb sights and anti-aircraft weaponry
Calcite
–
A one-inch calcite
rhomb that shows the
double image refraction property
Calcite
–
Crystal structure of calcite
Calcite
–
faceted calcite, oval cut, 1.12ct, Mexico.
Calcite
–
Doubly terminated calcite crystal.
40.
Dolomite
–
Dolomite is an anhydrous carbonate mineral composed of calcium magnesium carbonate, ideally CaMg2. The term is used for a sedimentary carbonate rock composed mostly of the mineral dolomite. An alternative name used for the dolomitic rock type is dolostone. Most probably the mineral dolomite was first described by Carl Linnaeus in 1768, nicolas-Théodore de Saussure first named the mineral in March 1792. The mineral dolomite crystallizes in the trigonal-rhombohedral system and it forms white, tan, gray, or pink crystals. Dolomite is a carbonate, having an alternating structural arrangement of calcium and magnesium ions. It does not rapidly dissolve or effervesce in dilute hydrochloric acid as calcite does, solid solution exists between dolomite, the iron-dominant ankerite and the manganese-dominant kutnohorite. Small amounts of iron in the give the crystals a yellow to brown tint. Manganese substitutes in the structure also up to three percent MnO. A high manganese content gives the crystals a rosy pink color, lead, zinc, and cobalt also substitute in the structure for magnesium. The mineral dolomite is closely related to huntite Mg3Ca4, because dolomite can be dissolved by slightly acidic water, areas of dolomite are important as aquifers and contribute to karst terrain formation. Modern dolomite formation has been found to occur under conditions in supersaturated saline lagoons along the Rio de Janeiro coast of Brazil, namely, Lagoa Vermelha. It is often thought that dolomite will develop only with the help of sulfate-reducing bacteria, however, low-temperature dolomite may occur in natural environments rich in organic matter and microbial cell surfaces. This occurs as a result of magnesium complexation by carboxyl groups associated with organic matter, vast deposits of dolomite are present in the geological record, but the mineral is relatively rare in modern environments. Reproducible, inorganic low-temperature syntheses of dolomite and magnesite were published for the first time in 1999, the general principle governing the course of this irreversible geochemical reaction has been coined breaking Ostwalds step rule. There is some evidence for an occurrence of dolomite. One example is that of the formation of dolomite in the bladder of a Dalmatian dog. In 2015, it was discovered that the direct crystallization of dolomite can occur from solution at temperatures between 60 and 220 °C
Dolomite
–
Dolomite and magnesite – Spain
Dolomite
–
Dolomite
Dolomite
–
Dolomite with
chalcopyrite from the
Tri-state district,
Cherokee County, Kansas (size: 11.4×7.2×4.6 cm)
41.
Magnetite
–
Magnetite is a mineral and one of the main iron ores. With the chemical formula Fe3O4, it is one of the oxides of iron, Magnetite is ferrimagnetic, it is attracted to a magnet and can be magnetized to become a permanent magnet itself. It is the most magnetic of all the minerals on Earth. Naturally-magnetized pieces of magnetite, called lodestone, will attract small pieces of iron, today it is mined as iron ore. Small grains of magnetite occur in almost all igneous and metamorphic rocks, Magnetite is black or brownish-black with a metallic luster, has a Mohs hardness of 5–6 and leaves a black streak. The chemical IUPAC name is iron oxide and the chemical name is ferrous-ferric oxide. In addition to rocks, magnetite also occurs in sedimentary rocks, including banded iron formations and in lake. Magnetite nanoparticles are also thought to form in soils, where they probably oxidize rapidly to maghemite, Magnetite has an inverse spinel crystal structure. As a member of the group, it can form solid solutions with similarly structured minerals, including ulvospinel. Titanomagnetite, also known as titaniferous magnetite, is a solution between magnetite and ulvospinel that crystallizes in many mafic igneous rocks. Titanomagnetite may undergo oxyexsolution during cooling, resulting in ingrowths of magnetite and ilmenite, Magnetite has been important in understanding the conditions under which rocks form. Magnetite reacts with oxygen to produce hematite, and the pair forms a buffer that can control oxygen fugacity. Commonly, igneous rocks contain solid solutions of both titanomagnetite and hemoilmenite or titanohematite, Magnetite also is produced from peridotites and dunites by serpentinization. Lodestones were used as a form of magnetic compass. At low temperatures, magnetite undergoes a crystal structure phase transition from a structure to a cubic structure known as the Verwey transition. The Verwey transition occurs around 121 K and is dependent on size, domain state. An isotropic point also occurs near the Verwey transition around 130 K, the Curie temperature of magnetite is 858 K. Magnetite is sometimes found in large quantities in beach sand. Such black sands are found in places, such as Lung Kwu Tan of Hong Kong, California of the United States
Magnetite
–
Magnetite and pyrite from Piedmont, Italy
Magnetite
–
Magnetite and other heavy minerals (dark) in a quartz
beach sand (
Chennai,
India).
Magnetite
–
Red gem-like crystals of
chondrodite with magnetite, Tilly Foster mine,
Brewster, New York (size 2.8 x 2.6 x 2.1 cm)
42.
Italy
–
Italy, officially the Italian Republic, is a unitary parliamentary republic in Europe. Located in the heart of the Mediterranean Sea, Italy shares open land borders with France, Switzerland, Austria, Slovenia, San Marino, Italy covers an area of 301,338 km2 and has a largely temperate seasonal and Mediterranean climate. Due to its shape, it is referred to in Italy as lo Stivale. With 61 million inhabitants, it is the fourth most populous EU member state, the Italic tribe known as the Latins formed the Roman Kingdom, which eventually became a republic that conquered and assimilated other nearby civilisations. The legacy of the Roman Empire is widespread and can be observed in the distribution of civilian law, republican governments, Christianity. The Renaissance began in Italy and spread to the rest of Europe, bringing a renewed interest in humanism, science, exploration, Italian culture flourished at this time, producing famous scholars, artists and polymaths such as Leonardo da Vinci, Galileo, Michelangelo and Machiavelli. The weakened sovereigns soon fell victim to conquest by European powers such as France, Spain and Austria. Despite being one of the victors in World War I, Italy entered a period of economic crisis and social turmoil. The subsequent participation in World War II on the Axis side ended in defeat, economic destruction. Today, Italy has the third largest economy in the Eurozone and it has a very high level of human development and is ranked sixth in the world for life expectancy. The country plays a prominent role in regional and global economic, military, cultural and diplomatic affairs, as a reflection of its cultural wealth, Italy is home to 51 World Heritage Sites, the most in the world, and is the fifth most visited country. The assumptions on the etymology of the name Italia are very numerous, according to one of the more common explanations, the term Italia, from Latin, Italia, was borrowed through Greek from the Oscan Víteliú, meaning land of young cattle. The bull was a symbol of the southern Italic tribes and was often depicted goring the Roman wolf as a defiant symbol of free Italy during the Social War. Greek historian Dionysius of Halicarnassus states this account together with the legend that Italy was named after Italus, mentioned also by Aristotle and Thucydides. The name Italia originally applied only to a part of what is now Southern Italy – according to Antiochus of Syracuse, but by his time Oenotria and Italy had become synonymous, and the name also applied to most of Lucania as well. The Greeks gradually came to apply the name Italia to a larger region, excavations throughout Italy revealed a Neanderthal presence dating back to the Palaeolithic period, some 200,000 years ago, modern Humans arrived about 40,000 years ago. Other ancient Italian peoples of undetermined language families but of possible origins include the Rhaetian people and Cammuni. Also the Phoenicians established colonies on the coasts of Sardinia and Sicily, the Roman legacy has deeply influenced the Western civilisation, shaping most of the modern world
Italy
–
The
Colosseum in Rome, built c. 70 – 80 AD, is considered one of the greatest works of
architecture and
engineering of ancient history.
Italy
–
Flag
Italy
–
The
Iron Crown of Lombardy, for centuries symbol of the
Kings of Italy.
Italy
–
Castel del Monte, built by German Emperor
Frederick II,
UNESCO World Heritage site
43.
Ural Mountains
–
The mountain range forms part of the conventional boundary between the continents of Europe and Asia. Vaygach Island and the islands of Novaya Zemlya form a continuation of the chain to the north into the Arctic Ocean. The mountains lie within the Ural geographical region and significantly overlap with the Ural Federal District and they have rich resources, including metal ores, coal, precious and semi-precious stones. Since the 18th century the mountains have contributed significantly to the sector of the Russian economy. As attested by Sigismund von Herberstein, in the 16th century Russians called the range by a variety of names derived from the Russian words for rock and it might have been a borrowing from either Turkic stone belt, or Ob-Ugric. From the 13th century, in Bashkortostan there has been a legend about a hero named Ural and he sacrificed his life for the sake of his people and they poured a stone pile over his grave, which later turned into the Ural Mountains. Possibilities include Bashkir үр elevation, upland or Mansi ур ала mountain peak, top of the mountain, tatischev believes that this oronym is set to belt and associates it with the Turkic verb oralu- gird. Dobrodomov suggests a transition from Aral to Ural explained on the basis of ancient Bulgar-Chuvash dialects, hawks believes that the name goes back to the Bashkir folklore Ural-Batyr. Shumilov suggested a Mongolian origin, Khural Uul, that is, the Evenk geographical term era mountain has also been theorized. Finno-Ugrist scholars consider Ural deriving from the Mansi word urr meaning a mountain, turkologists, on the other hand, have achieved majority support for their assertion that ural in Tatar means a belt, and recall that an earlier name for the range was stone belt. During the next few centuries Novgorodians engaged in fur trading with the population and collected tribute from Yugra and Great Perm. The rivers Chusovaya and Belaya were first mentioned in the chronicles of 1396 and 1468, in 1430 the town of Solikamsk was founded on the Kama at the foothills of the Ural, where salt was produced in open pans. Ivan III of Moscow captured Perm, Pechora and Yugra from the declining Novgorod Republic in 1472, with the excursions of 1483 and 1499–1500 across the Ural Moscow managed to subjugate Yugra completely. The Middle and Southern Ural were still largely unavailable and unknown to the Russian or Western European geographers, the Stroganovs land provided the staging ground for Yermaks incursion into Siberia. Yermak crossed the Ural from the Chusovaya to the Tagil around 1581, in 1597 Babinovs road was built across the Ural from Solikamsk to the valley of the Tura, where the town of Verkhoturye was founded in 1598. Customs was established in Verkhoturye shortly thereafter and the road was made the legal connection between European Russia and Siberia for a long time. In 1648 the town of Kungur was founded at the foothills of the Middle Ural. During the 17th century the first deposits of iron and copper ores, mica, gemstones, iron and copper smelting works emerged
Ural Mountains
–
Verkhoturye in 1910
Ural Mountains
Ural Mountains
–
Yugyd Va National Park
Ural Mountains
–
Mountain formation near Saranpaul, Nether-Polar Urals
44.
Russia
–
Russia, also officially the Russian Federation, is a country in Eurasia. The European western part of the country is more populated and urbanised than the eastern. Russias capital Moscow is one of the largest cities in the world, other urban centers include Saint Petersburg, Novosibirsk, Yekaterinburg, Nizhny Novgorod. Extending across the entirety of Northern Asia and much of Eastern Europe, Russia spans eleven time zones and incorporates a range of environments. It shares maritime borders with Japan by the Sea of Okhotsk, the East Slavs emerged as a recognizable group in Europe between the 3rd and 8th centuries AD. Founded and ruled by a Varangian warrior elite and their descendants, in 988 it adopted Orthodox Christianity from the Byzantine Empire, beginning the synthesis of Byzantine and Slavic cultures that defined Russian culture for the next millennium. Rus ultimately disintegrated into a number of states, most of the Rus lands were overrun by the Mongol invasion. The Soviet Union played a role in the Allied victory in World War II. The Soviet era saw some of the most significant technological achievements of the 20th century, including the worlds first human-made satellite and the launching of the first humans in space. By the end of 1990, the Soviet Union had the second largest economy, largest standing military in the world. It is governed as a federal semi-presidential republic, the Russian economy ranks as the twelfth largest by nominal GDP and sixth largest by purchasing power parity in 2015. Russias extensive mineral and energy resources are the largest such reserves in the world, making it one of the producers of oil. The country is one of the five recognized nuclear weapons states and possesses the largest stockpile of weapons of mass destruction, Russia is a great power as well as a regional power and has been characterised as a potential superpower. The name Russia is derived from Rus, a state populated mostly by the East Slavs. However, this name became more prominent in the later history, and the country typically was called by its inhabitants Русская Земля. In order to distinguish this state from other states derived from it, it is denoted as Kievan Rus by modern historiography, an old Latin version of the name Rus was Ruthenia, mostly applied to the western and southern regions of Rus that were adjacent to Catholic Europe. The current name of the country, Россия, comes from the Byzantine Greek designation of the Kievan Rus, the standard way to refer to citizens of Russia is Russians in English and rossiyane in Russian. There are two Russian words which are translated into English as Russians
Russia
–
Kievan Rus' in the 11th century
Russia
–
Flag
Russia
–
The
Baptism of Kievans, by
Klavdy Lebedev
Russia
–
Sergius of Radonezh blessing
Dmitry Donskoy in
Trinity Sergius Lavra, before the
Battle of Kulikovo, depicted in a painting by
Ernst Lissner
45.
Arizona
–
Arizona is a state in the southwestern region of the United States. It is also part of the Western United States and the Mountain West states and it is the sixth largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix, Arizona is one of the Four Corners states. It has borders with New Mexico, Utah, Nevada, California, and Mexico, Arizonas border with Mexico is 389 miles long, on the northern border of the Mexican states of Sonora and Baja California. Arizona is the 48th state and last of the states to be admitted to the Union. Historically part of the territory of Alta California in New Spain, after being defeated in the Mexican–American War, Mexico ceded much of this territory to the United States in 1848. The southernmost portion of the state was acquired in 1853 through the Gadsden Purchase, Southern Arizona is known for its desert climate, with very hot summers and mild winters. There are ski resorts in the areas of Flagstaff, Alpine, in addition to the Grand Canyon National Park, there are several national forests, national parks, and national monuments. To the European settlers, their pronunciation sounded like Arissona, the area is still known as alĭ ṣonak in the Oodham language. Another possible origin is the Basque phrase haritz ona, as there were numerous Basque sheepherders in the area, There is a misconception that the states name originated from the Spanish term Árida Zona. See also lists of counties, islands, rivers, lakes, state parks, national parks, Arizona is in the Southwestern United States as one of the Four Corners states. Arizona is the sixth largest state by area, ranked after New Mexico, of the states 113,998 square miles, approximately 15% is privately owned. The remaining area is public forest and park land, state trust land, Arizona is well known for its desert Basin and Range region in the states southern portions, which is rich in a landscape of xerophyte plants such as the cactus. This regions topography was shaped by volcanism, followed by the cooling-off. Its climate has hot summers and mild winters. The state is well known for its pine-covered north-central portion of the high country of the Colorado Plateau. Like other states of the Southwest United States, Arizona has an abundance of mountains, despite the states aridity, 27% of Arizona is forest, a percentage comparable to modern-day France or Germany. The worlds largest stand of pine trees is in Arizona
Arizona
–
Saguaro cactus flowers and buds after a wet winter. This is Arizona's official State Flower.
Arizona
–
Flag
Arizona
–
The
Horseshoe Bend of the
Colorado River.
Arizona
–
West Mitten at
Monument Valley
46.
California
–
California is the most populous state in the United States and the third most extensive by area. Located on the western coast of the U. S, California is bordered by the other U. S. states of Oregon, Nevada, and Arizona and shares an international border with the Mexican state of Baja California. Los Angeles is Californias most populous city, and the second largest after New York City. The Los Angeles Area and the San Francisco Bay Area are the nations second- and fifth-most populous urban regions, California also has the nations most populous county, Los Angeles County, and its largest county by area, San Bernardino County. The Central Valley, an agricultural area, dominates the states center. What is now California was first settled by various Native American tribes before being explored by a number of European expeditions during the 16th and 17th centuries, the Spanish Empire then claimed it as part of Alta California in their New Spain colony. The area became a part of Mexico in 1821 following its war for independence. The western portion of Alta California then was organized as the State of California, the California Gold Rush starting in 1848 led to dramatic social and demographic changes, with large-scale emigration from the east and abroad with an accompanying economic boom. If it were a country, California would be the 6th largest economy in the world, fifty-eight percent of the states economy is centered on finance, government, real estate services, technology, and professional, scientific and technical business services. Although it accounts for only 1.5 percent of the states economy, the story of Calafia is recorded in a 1510 work The Adventures of Esplandián, written as a sequel to Amadis de Gaula by Spanish adventure writer Garci Rodríguez de Montalvo. The kingdom of Queen Calafia, according to Montalvo, was said to be a land inhabited by griffins and other strange beasts. This conventional wisdom that California was an island, with maps drawn to reflect this belief, shortened forms of the states name include CA, Cal. Calif. and US-CA. Settled by successive waves of arrivals during the last 10,000 years, various estimates of the native population range from 100,000 to 300,000. The Indigenous peoples of California included more than 70 distinct groups of Native Americans, ranging from large, settled populations living on the coast to groups in the interior. California groups also were diverse in their organization with bands, tribes, villages. Trade, intermarriage and military alliances fostered many social and economic relationships among the diverse groups, the first European effort to explore the coast as far north as the Russian River was a Spanish sailing expedition, led by Portuguese captain Juan Rodríguez Cabrillo, in 1542. Some 37 years later English explorer Francis Drake also explored and claimed a portion of the California coast in 1579. Spanish traders made unintended visits with the Manila galleons on their trips from the Philippines beginning in 1565
California
–
A forest of redwood trees in
Redwood National Park
California
–
Flag
California
–
Mount Shasta
California
–
Aerial view of the
California Central Valley
47.
Dnipropetrovsk Oblast
–
Dnipropetrovsk Oblast is an oblast of central Ukraine, the most important industrial region of the country. It was created on February 27,1932, Dnipropetrovsk has a population of about 3,307, 795 , approximately 80% of whom live centering on administrative center of Dnipro, Kryvyi Rih, Kamianske, Nikopol. The Dnieper River runs through the oblast, the Dnipropetrovsk Oblast is located in southeastern Ukraine. The area of the oblast, comprises about 5. 3% of the area of the country. Its longitude from north to south is 130 km, from east to west –300 km, black Sea Lowland almost completely within the south oblast, covering half of its territory. It is 11 km in diameter and the age is estimated to be 280 ±10 million years, the crater is not exposed at the surface. The Dnieper Upland contains a number of minerals including iron, manganese, granite, graphite, brown coal, Kryvbas is an important economic region, specializing in iron ore mining and the steel industry. It is arguably the main iron ore region of Eastern Europe, named after the city of Kryvyi Rih, the region occupies the southwestern part of the Dnipropetrovsk, as well as a small neighbouring part of the Kirovohrad Oblast. The region possesses major deposits of ore and some other metallurgical ores. To exploit them, several mining companies were founded here in the middle of the 20th century. Most of them are located in Kryvyi Rih itself, which is the longest city in Europe, at the beginning of the 15th century, Tatar tribes inhabiting the right bank of the Dnieper were driven away by the Grand Duchy of Lithuania. However, by the century, the Nogai and the Crimean Khanate invaded these lands. The Grand Duchy of Lithuania and the Crimean Khanate agreed to a border along the Dnieper and it was in this time that there appeared a new force–the Cossacks, armed freemen not subject to any feudal lord– who were to soon dominate the region. They later became known as Zaporozhian Cossacks, from Zaporizhia–the lands south of Prydniprovye– which translates as the Land Beyond the Weirs ) and this was a period of raids and fighting causing considerable devastation and depopulation in that area, the area became known as the Wilderness. On the night of 3 or 4 August 1635, the Cossacks of Ivan Sulyma captured the fort by surprise, burning it down, the fort was rebuilt by French engineer Guillaume Le Vasseur de Beauplan for the Polish Government in 1638, and had a mercenary garrison. Kodak was captured by Zaporozhian Cossacks on 1 October 1648, and was garrisoned by the Cossacks until its demolition in accordance with the Treaty of the Pruth in 1711, under the Treaty of Pereyaslav of 1654, the territory became part of the Russian Empire. The city of Yekaterinoslav was founded in 1776, not in the current location, in December 1796, Paul I reestablished the Novorossiysk Governorate, mostly with land from the former Yekaterinoslav Viceroyalty. In 1802, this province was divided into the Nikolayev Governorate, Yekaterinoslav Governorate, and its capital was the city of Yekaterinoslav created in 1802 out the Yekaterinoslav Vice-regency
Dnipropetrovsk Oblast
–
1648 map of
Beauplan where
Dzikie Pole identified in upper portion of the map.
Dnipropetrovsk Oblast
Dnipropetrovsk Oblast
–
Building of Dnipropetrovsk Regional Administration
Dnipropetrovsk Oblast
–
Dnipropetrovsk
48.
Ukraine
–
Ukraine is currently in territorial dispute with Russia over the Crimean Peninsula which Russia annexed in 2014 but which Ukraine and most of the international community recognise as Ukrainian. Including Crimea, Ukraine has an area of 603,628 km2, making it the largest country entirely within Europe and it has a population of about 42.5 million, making it the 32nd most populous country in the world. The territory of modern Ukraine has been inhabited since 32,000 BC, during the Middle Ages, the area was a key centre of East Slavic culture, with the powerful state of Kievan Rus forming the basis of Ukrainian identity. Following its fragmentation in the 13th century, the territory was contested, ruled and divided by a variety of powers, including Lithuania, Poland, the Ottoman Empire, Austria-Hungary, and Russia. A Cossack republic emerged and prospered during the 17th and 18th centuries, two brief periods of independence occurred during the 20th century, once near the end of World War I and another during World War II. Before its independence, Ukraine was typically referred to in English as The Ukraine, following independence, Ukraine declared itself a neutral state. Nonetheless it formed a limited partnership with the Russian Federation and other CIS countries. In the 2000s, the government began leaning towards NATO, and it was later agreed that the question of joining NATO should be answered by a national referendum at some point in the future. Former President Viktor Yanukovych considered the current level of co-operation between Ukraine and NATO sufficient, and was against Ukraine joining NATO and these events formed the background for the annexation of Crimea by Russia in March 2014, and the War in Donbass in April 2014. On 1 January 2016, Ukraine applied the economic part of the Deep, Ukraine has long been a global breadbasket because of its extensive, fertile farmlands and is one of the worlds largest grain exporters. The diversified economy of Ukraine includes a heavy industry sector, particularly in aerospace. Ukraine is a republic under a semi-presidential system with separate powers, legislative, executive. Its capital and largest city is Kiev, taking into account reserves and paramilitary personnel, Ukraine maintains the second-largest military in Europe after that of Russia. Ukrainian is the language and its alphabet is Cyrillic. The dominant religion in the country is Eastern Orthodoxy, which has strongly influenced Ukrainian architecture, literature, there are different hypotheses as to the etymology of the name Ukraine. According to the older and most widespread hypothesis, it means borderland, while more recently some studies claim a different meaning, homeland or region. The Ukraine now implies disregard for the sovereignty, according to U. S. ambassador William Taylor. Neanderthal settlement in Ukraine is seen in the Molodova archaeological sites include a mammoth bone dwelling
Ukraine
–
Gold
Scythian pectoral, or neckpiece, from a royal
kurgan in
Ordzhonikidze, dated to the 4th century BC
Ukraine
–
Flag
Ukraine
–
Principalities of
Kievan Rus', 1054-1132
Ukraine
–
The baptism of the Grand Prince Vladimir led to the adoption of Christianity in
Kievan Rus'.
49.
Antiferromagnetic
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This is, like ferromagnetism and ferrimagnetism, a manifestation of ordered magnetism. Generally, antiferromagnetic order may exist at low temperatures, vanishing at and above a certain temperature. Above the Néel temperature, the material is typically paramagnetic, when no external field is applied, the antiferromagnetic structure corresponds to a vanishing total magnetization. Although the net magnetization should be zero at a temperature of absolute zero, the magnetic susceptibility of an antiferromagnetic material typically shows a maximum at the Néel temperature. In contrast, at the transition between the ferromagnetic to the paramagnetic phases the susceptibility will diverge, in the antiferromagnetic case, a divergence is observed in the staggered susceptibility. Various microscopic interactions between the magnetic moments or spins may lead to antiferromagnetic structures, in the simplest case, one may consider an Ising model on a bipartite lattice, e. g. the simple cubic lattice, with couplings between spins at nearest neighbor sites. Depending on the sign of that interaction, ferromagnetic or antiferromagnetic order will result, geometrical frustration or competing ferro- and antiferromagnetic interactions may lead to different and, perhaps, more complicated magnetic structures. Antiferromagnetic materials occur commonly among transition metal compounds, especially oxides, examples include hematite, metals such as chromium, alloys such as iron manganese, and oxides such as nickel oxide. There are also numerous examples among high nuclearity metal clusters, organic molecules can also exhibit antiferromagnetic coupling under rare circumstances, as seen in radicals such as 5-dehydro-m-xylylene. Unlike ferromagnetism, anti-ferromagnetic interactions can lead to multiple optimal states, in one dimension, the anti-ferromagnetic ground state is an alternating series of spins, up, down, up, down, etc. Yet in two dimensions, multiple ground states can occur, consider an equilateral triangle with three spins, one on each vertex. If each spin can take on two values, there are 23 =8 possible states of the system, six of which are ground states. The two situations which are not ground states are all three spins are up or are all down. In any of the six states, there will be two favorable interactions and one unfavorable one. This illustrates frustration, the inability of the system to find a ground state. This type of behavior has been found in minerals that have a crystal stacking structure such as a Kagome lattice or hexagonal lattice. Synthetic antiferromagnets are artificial antiferromagnets consisting of two or more thin ferromagnetic layers separated by a nonmagnetic layer, due to dipole coupling of the ferromagnetic layers results in antiparallel alignment of the magnetization of the ferromagnets. Antiferromagnetism plays a role in giant magnetoresistance, as had been discovered in 1988 by the Nobel prize winners Albert Fert
Antiferromagnetic
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Antiferromagnetic ordering
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Melanite
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Andradite is a species of the garnet group. It is a nesosilicate, with formula Ca3Fe2Si3O12, Andradite includes three varieties, Melanite, Black in color, referred to as titanian andradite. Demantoid, Vivid green in color, one of the most valuable, topazolite, Yellow-green in color and sometimes of high enough quality to be cut into a faceted gemstone, it is rarer than demantoid. It was first described in 1868 for an occurrence in Drammen, Buskerud, Andradite was named after the Brazilian statesman, naturalist, professor and poet José Bonifácio de Andrade e Silva. It occurs in skarns developed in contact metamorphosed impure limestones or calcic igneous rocks, in chlorite schists and serpentinites, associated minerals include vesuvianite, chlorite, epidote, spinel, calcite, dolomite and magnetite. It is found in Italy, the Ural Mountains of Russia, Arizona and California, like the other garnets, andradite crystallizes in the cubic space group, with unit-cell parameter of 12.051 Å at 100 K. The spin structure of andradite contains two mutually canted equivalent antiferromagnetic sublattices below the Néel temperature, media related to Andradite at Wikimedia Commons
Melanite
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single crystal (4.2cm) - Diakon, Nioro du Sahel Circle, Kayes Region, Mali
Melanite
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Black crystals of andradite: melanite
Media related to Andradite at Wikimedia Commons
