1.
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
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
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
4.
Monoclinic crystal system
–
In crystallography, the monoclinic crystal system is one of the 7 crystal systems. A crystal system is described by three vectors, in the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic system. They form a rectangular prism with a parallelogram as its base, hence two vectors are perpendicular, while the third vector meets the other two at an angle other than 90°. There is only one monoclinic Bravais lattice in two dimensions, the oblique lattice, two monoclinic Bravais lattices exist, the primitive monoclinic and the centered monoclinic lattices. In this axis setting, the primitive and base-centered lattices interchange in centering type, sphenoidal is also monoclinic hemimorphic, Domatic is also monoclinic hemihedral, Prismatic is also monoclinic normal. Crystal structure Hurlbut, Cornelius S. Klein, Cornelis, hahn, Theo, ed. International Tables for Crystallography, Volume A, Space Group Symmetry
5.
Crystallographic point group
–
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
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
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
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
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
10.
Crystal twinning
–
Crystal twinning occurs when two separate crystals share some of the same crystal lattice points in a symmetrical manner. The result is an intergrowth of two separate crystals in a variety of specific configurations, a twin boundary or composition surface separates the two crystals. Crystallographers classify twinned crystals by a number of twin laws and these twin laws are specific to the crystal system. The type of twinning can be a tool in mineral identification. Twinning can often be a problem in X-ray crystallography, as a crystal does not produce a simple diffraction pattern. Simple twinned crystals may be contact twins or penetration twins, contact twins share a single composition surface often appearing as mirror images across the boundary. Plagioclase, quartz, gypsum, and spinel often exhibit contact twinning, merohedral twinning occurs when the lattices of the contact twins superimpose in three dimensions, such as by relative rotation of one twin from the other. In penetration twins the individual crystals have the appearance of passing through each other in a symmetrical manner, orthoclase, staurolite, pyrite, and fluorite often show penetration twinning. If several twin crystal parts are aligned by the same twin law they are referred to as multiple or repeated twins, if these multiple twins are aligned in parallel they are called polysynthetic twins. When the multiple twins are not parallel they are cyclic twins, albite, calcite, and pyrite often show polysynthetic twinning. Closely spaced polysynthetic twinning is often observed as striations or fine lines on the crystal face. Rutile, aragonite, cerussite, and chrysoberyl often exhibit cyclic twinning, 2-normal twin, -when the twin plane and compositional plane lies noramally. 3-complex twin, -combination of parallel twinning and normal twinning on one compositional plane, there are three modes of formation of twinned crystals. Growth twins are the result of an interruption or change in the lattice during formation or growth due to a possible deformation from a larger substituting ion, deformation or gliding twins are the result of stress on the crystal after the crystal has formed. If a FCC metal like aluminum experiences extreme stresses, it will experience twinning as seen in the case of explosions, deformation twinning is a common result of regional metamorphism. Crystals that grow adjacent to each other may be aligned to resemble twinning and this parallel growth simply reduces system energy and is not twinning. Twin boundaries occur when two crystals of the same type intergrow, so only a slight misorientation exists between them. It is a highly symmetrical interface, often with one crystal the mirror image of the other, also and this is also a much lower-energy interface than the grain boundaries that form when crystals of arbitrary orientation grow together
11.
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
12.
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
13.
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
14.
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
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
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
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
18.
Birefringence
–
Birefringence is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light. These optically anisotropic materials are said to be birefringent, the birefringence is often quantified as the maximum difference between refractive indices exhibited by the material. Crystals with non-cubic crystal structures are often birefringent, as are plastics under mechanical stress and this effect was first described by the Danish scientist Rasmus Bartholin in 1669, who observed it in calcite, a crystal having one of the strongest birefringences. A mathematical description of wave propagation in a birefringent medium is presented below, following is a qualitative explanation of the phenomenon. Thus rotating the material around this axis does not change its optical behavior and this special direction is known as the optic axis of the material. Light whose polarization is perpendicular to the axis is governed by a refractive index no. Light whose polarization is in the direction of the optic axis sees an optical index ne, for any ray direction there is a linear polarization direction perpendicular to the optic axis, and this is called an ordinary ray. The magnitude of the difference is quantified by the birefringence, Δ n = n e − n o, the propagation of the ordinary ray is simply described by no as if there were no birefringence involved. However the extraordinary ray, as its name suggests, propagates unlike any wave in an optical material. Its refraction at a surface can be using the effective refractive index. However it is in fact an inhomogeneous wave whose power flow is not exactly in the direction of the wave vector and this causes an additional shift in that beam, even when launched at normal incidence, as is popularly observed using a crystal of calcite as photographed above. Rotating the calcite crystal will cause one of the two images, that of the ray, to rotate slightly around that of the ordinary ray. When the light propagates either along or orthogonal to the optic axis, in the first case, both polarizations see the same effective refractive index, so there is no extraordinary ray. In the second case the extraordinary ray propagates at a different phase velocity but is not an inhomogeneous wave, for instance, a quarter-wave plate is commonly used to create circular polarization from a linearly polarized source. The case of so-called biaxial crystals is substantially more complex and these are characterized by three refractive indices corresponding to three principal axes of the crystal. For most ray directions, both polarizations would be classified as extraordinary rays but with different effective refractive indices, being extraordinary waves, however, the direction of power flow is not identical to the direction of the wave vector in either case. The two refractive indices can be determined using the index ellipsoids for given directions of the polarization, note that for biaxial crystals the index ellipsoid will not be an ellipsoid of revolution but is described by three unequal principle refractive indices nα, nβ and nγ. Thus there is no axis around which a rotation leaves the optical properties invariant, for this reason, birefringent materials with three distinct refractive indices are called biaxial
19.
Pleochroism
–
Pleochroism is an optical phenomenon in which a substance appears to be different colors when observed at different angles, especially with polarized light. Anisotropic crystals will have properties that vary with the direction of light. The polarization of light determines the direction of the electric field and these kinds of crystals have one or two optical axes. If absorption of light varies with the relative to the optical axis in a crystal then pleochroism results. Anisotropic crystals have double refraction of light where light of different polarizations is bent different amounts by the crystal, the components of a divided light beam follow different paths within the mineral and travel at different speeds. When the mineral is observed at some angle, light following some combination of paths and polarizations will be present, at another angle, the light passing through the crystal will be composed of another combination of light paths and polarizations, each with their own color. The light passing through the mineral will therefore have different colors when it is viewed from different angles, tetragonal, trigonal and hexagonal minerals can only show two colors and are called dichroic. Orthorhombic, monoclinic and triclinic crystals can show three and are trichroic, for example, hypersthene, with two optical axes, can have red, yellow or blue appearance when oriented in three different ways in three-dimensional space. Tourmaline is notable for exhibiting strong pleochroism, gems are sometimes cut and set either to display pleochroism or to hide it, depending on the colors and their attractiveness. The pleochroic colours are at their maximum when light is polarized parallel with a crystallographic axis, the axes are designated X, Y and Z. These axes can be determined from the appearance of a crystal in an interference pattern. Where there are two axes, the acute bisection of the axes gives Z for positive minerals and X for negative minerals. Perpendicular to these is the Y axis, the colour is measured with the polarization parallel to each direction. An absorption formula records the amount of parallel to each axis in the form of X < Y < Z with the left most having the least absorption. Minerals that are very similar often have very different pleochroic color schemes. In such cases, a section of the mineral is used and examined under polarized transmitted light with a petrographic microscope. Another device using this property to identify minerals is the dichroscope
20.
Amphibole
–
Amphiboles can be green, black, colorless, white, yellow, blue, or brown. The International Mineralogical Association currently classifies amphiboles as a mineral supergroup, amphiboles crystallize into two crystal systems, monoclinic and orthorhombic. In chemical composition and general characteristics they are similar to the pyroxenes, the chief differences from pyroxenes are that amphiboles contain essential hydroxyl or halogen and the basic structure is a double chain of tetrahedra. Most apparent, in specimens, is that amphiboles form oblique cleavage planes. Amphiboles are also less dense than the corresponding pyroxenes. In optical characteristics, many amphiboles are distinguished by their stronger pleochroism, amphiboles are the primary constituent of amphibolites. Amphiboles are minerals of either igneous or metamorphic origin, in the former case occurring as constituents of rocks, such as granite, diorite, andesite. Calcium is sometimes a constituent of naturally occurring amphiboles and those of metamorphic origin include examples such as those developed in limestones by contact metamorphism and those formed by the alteration of other ferromagnesian minerals. Pseudomorphs of amphibole after pyroxene are known as uralite, the name amphibole was used by René Just Haüy to include tremolite, actinolite, tourmaline and hornblende. The group was so named by Haüy in allusion to the variety, in composition and appearance. This term has since applied to the whole group. Numerous sub-species and varieties are distinguished, the important of which are tabulated below in two series. The formulae of each will be seen to be built on the general double-chain silicate formula RSi4O11, four of the amphibole minerals are among the minerals commonly called asbestos. These are, anthophyllite, riebeckite, cummingtonite/grunerite series, and actinolite/tremolite series, the cummingtonite/grunerite series is often termed amosite or brown asbestos, riebeckite is known as crocidolite or blue asbestos. These are generally called amphibole asbestos, anthophyllite occurs as brownish, fibrous or lamellar masses with hornblende in mica-schist at Kongsberg in Norway and some other localities. An aluminous related species is known as gedrite and a deep green Russian variety containing little iron as kupfferite, hornblende is an important constituent of many igneous rocks. It is also an important constituent of amphibolites formed by metamorphism of basalt, actinolite is an important and common member of the monoclinic series, forming radiating groups of acicular crystals of a bright green or greyish-green color. It occurs frequently as a constituent of greenschists, the name is a translation of the old German word Strahlstein
21.
Anthophyllite
–
Anthophyllite is an amphibole mineral, ☐Mg2Mg5Si8O222, magnesium iron inosilicate hydroxide. Some forms of anthophyllite are lamellar or fibrous and are classed as asbestos, the name is derived from the Latin word anthophyllum, meaning clove, an allusion to the most common color of the mineral. Anthophylite is the product of metamorphism of rocks, especially ultrabasic igneous rocks. It also forms as a retrograde product rimming relict orthopyroxenes and olivine, anthophyllite also occurs as a retrograde metamorphic mineral derived from ultramafic rocks along with serpentinite. Geographically, it occurs in Pennsylvania, southwestern New Hampshire, central Massachusetts, Franklin, North Carolina, anthophyllite is formed by the breakdown of talc in ultramafic rocks in the presence of water and carbon dioxide as a prograde metamorphic reaction. The partial pressure of carbon dioxide in aqueous solution favors production of anthophyllite, higher partial pressures of CO2 reduces the temperature of the anthophyllite-in isograd. Thus, metamorphic assemblages of ultramafic rocks containing anthophyllite are indicative of at least greenschist facies metamorphism in the presence of carbon dioxide bearing metamorphic fluids, similarly, the need for substantial components of carbon dioxide in metamorphic fluid restricts the appearance of anthophyllite as a retrograde mineral. The usual metamorphic assemblage of retrograde-altered ultramafic rocks is usually a serpentinite or talc-magnesite assemblage. Retrograde anthophyllite is present most usually in shear zones where fracturing and shearing of the rocks provides a conduit for carbonated fluids during retrogression, fibrous anthophyllite is one of the six recognised types of asbestos. It was mined in Finland and also in Matsubase, Japan where a large-scale open-cast asbestos mine, in Finland anthophyllite asbestos was mined in two mines, the larger one Paakkila in the Tuusniemi commune started in 1918 and closed in 1975 due to the dust problems. The smaller mine, Maljasalmi in the commune of Outokumpu, was mined from 1944 to 1952, the anthophyllite was used in asbestos cement and for insulation, roofing material etc. In the UK anthophyllite is most commonly found in composite flooring, anthophyllite is also known as azbolen asbestos
22.
Magnesium
–
Magnesium is a chemical element with symbol Mg and atomic number 12. Magnesium is the ninth most abundant element in the universe and it is produced in large, aging stars from the sequential addition of three helium nuclei to a carbon nucleus. When such stars explode as supernovas, much of the magnesium is expelled into the medium where it may recycle into new star systems. Magnesium is the eighth most abundant element in the Earths crust and the fourth most common element in the Earth, making up 13% of the planets mass and it is the third most abundant element dissolved in seawater, after sodium and chlorine. Magnesium occurs naturally only in combination with elements, where it invariably has a +2 oxidation state. The free element can be produced artificially, and is highly reactive, the free metal burns with a characteristic brilliant-white light. The metal is now obtained mainly by electrolysis of magnesium salts obtained from brine, Magnesium is less dense than aluminium, and the alloy is prized for its combination of lightness and strength. Magnesium is the eleventh most abundant element by mass in the body and is essential to all cells. Magnesium ions interact with polyphosphate compounds such as ATP, DNA, hundreds of enzymes require magnesium ions to function. Magnesium compounds are used medicinally as common laxatives, antacids, elemental magnesium is a gray-white lightweight metal, two-thirds the density of aluminium. Magnesium has the lowest melting and the lowest boiling point 1,363 K of all the alkaline earth metals, Magnesium reacts with water at room temperature, though it reacts much more slowly than calcium, a similar group 2 metal. When submerged in water, hydrogen bubbles form slowly on the surface of the metal—though, if powdered, the reaction occurs faster with higher temperatures. Magnesiums reversible reaction with water can be harnessed to store energy, Magnesium also reacts exothermically with most acids such as hydrochloric acid, producing the metal chloride and hydrogen gas, similar to the HCl reaction with aluminium, zinc, and many other metals. Magnesium is highly flammable, especially when powdered or shaved into thin strips, flame temperatures of magnesium and magnesium alloys can reach 3,100 °C, although flame height above the burning metal is usually less than 300 mm. Once ignited, such fires are difficult to extinguish, with combustion continuing in nitrogen, carbon dioxide, Magnesium may also be used as an igniter for thermite, a mixture of aluminium and iron oxide powder that ignites only at a very high temperature. When burning in air, magnesium produces a light that includes strong ultraviolet wavelengths. Magnesium powder was used for illumination in the early days of photography. Later, magnesium filament was used in electrically ignited single-use photography flashbulbs, Magnesium powder is used in fireworks and marine flares where a brilliant white light is required
23.
Metastability
–
In physics, metastability denotes the phenomenon when a dynamical system spends an extended time in a configuration other than the systems state of least energy. During a metastable state of finite lifetime, all state-describing parameters reach, a conceptual analogy may be drawn with a ball resting in a hollow on a slope. Small perturbations will result in the ball settling back into its current hollow, isomerisation is another common example of metastability. Higher energy isomers are long lived as they are prevented from rearranging to their ground state by barriers in the potential energy. The metastability concept originated in the physics of first-order phase transitions and it then acquired new meaning in the study of aggregated subatomic particles or in molecules, macromolecules or clusters of atoms and molecules. Later, it was borrowed for the study of decision-making and information transmission systems, many complex natural and man-made systems can demonstrate metastability. Metastability is common in physics and chemistry – from an atom to statistical ensembles of molecules at molecular levels or as a whole, the abundance of states is more prevalent as the systems grow larger and/or if the forces of their mutual interaction are spatially less uniform or more diverse. In these systems, the equivalent of thermal fluctuations in molecular systems is the noise that affects signal propagation. Non-equilibrium thermodynamics is a branch of physics that studies the dynamics of statistical ensembles of molecules via unstable states, being stuck in a thermodynamic trough without being at the lowest energy state is known as having kinetic stability or being kinetically persistent. The particular motion or kinetics of the atoms involved has resulted in getting stuck, metastable states of matter range from melting solids, boiling liquids and sublimating solids to supercooled liquids or superheated liquid-gas mixtures. Extremely pure, supercooled water stays liquid below 0 °C and remains so until applied vibrations or condensing seed doping initiates crystallization centers and this is a common situation for the droplets of atmospheric clouds. Metastable phases are common in condensed matter, for example, diamond is a metastable form of carbon at standard temperature and pressure. It can be converted to graphite, but only after overcoming an activation energy – an intervening hill, martensite is a metastable phase used to control the hardness of most steel. The bonds between the blocks of polymers such as DNA, RNA and proteins are also metastable. Metastable polymorphs of silica are commonly observed, in some cases, such as in the allotropes of solid boron, acquiring a sample of the stable phase is difficult. Generally speaking, emulsions/colloidal systems and glasses are metastable, sandpiles are one system which can exhibit metastability if a steep slope or tunnel is present. Sand grains form a pile due to friction and it is possible for an entire large sand pile to reach a point where it is stable, but the addition of a single grain causes large parts of it to collapse. The avalanche is a problem with large piles of snow
24.
Arfvedsonite
–
Arfvedsonite is a sodium amphibole mineral with composition. It crystallizes in the monoclinic crystal system and typically occurs as greenish black to bluish grey fibrous to radiating or stellate prisms. It is a rare mineral occurring in nepheline syenite intrusions and agpaitic pegmatites and granites as the Golden Horn batholith in Okanogan County. Occurrences include Mont Saint-Hilaire, Quebec, Canada, the Ilímaussaq complex in Southern Greenland and its mineral association includes nepheline, albite, aegirine, riebeckite, katophorite and quartz. Arfvedsonite was discovered in 1823 and named for the Swedish chemist Johan August Arfwedson, List of minerals List of minerals named after people Deer, W. A. R. A. Howie, and J. Zussman Rock-forming Minerals, v.2, Chain Silicates, p. 364–374 Mineral Galleries
25.
Glaucophane
–
Glaucophane is the name of a mineral and a mineral group belonging to the sodic amphibole supergroup of the double chain inosilicates, with the chemical formula ☐Na2Si8O222. Glaucophane crystallizes in the monoclinic system, glaucophane is named for its typical blue color. In Greek, glaucophane means blue appearing, as the major mineral component, it is glaucophanes color that gives the blueschist metamorphic rock type its name. The blue color is very diagnostic for this species, glaucophane, along with the closely related mineral riebeckite, to which it forms a series with, and their intermediate crossite, are the only well known amphiboles that are commonly blue. Glaucophane forms a solid solution series with ferroglaucophane, Na23Al2Si8O222, glaucophane is the magnesium-rich endmember and ferroglaucophane is the iron-rich endmember. Ferroglaucophane is similar to glaucophane but is denser and hence increased specific gravity. The two endmembers are indistinguishable in hand specimens and are strongly pleochroic, glaucophanes hardness is 5 -6 and its specific gravity is approximately 3 -3.2. The blueschist metamorphic facies gets its name from abundant blue minerals glaucophane and this material has undergone intense pressure and moderate heat as it was subducted downward toward the mantle. Glaucophane is also found in eclogites that have undergone retrograde metamorphism, there is also a rare amphibole called holmquistite, chemical formula Li2Mg3Al2Si8O222, which occurs only in lithium-rich continental rocks. For many years, holmquistite was mistaken for glaucophane, as the two look identical in thin section
26.
Riebeckite
–
Riebeckite is a sodium-rich member of the amphibole group of silicate minerals, chemical formula Na2Si8O222. It forms a solid solution series with magnesioriebeckite and it crystallizes in the monoclinic system, usually as long prismatic crystals showing a diamond-shaped cross section, but also in fibrous, bladed, acicular, columnar, and radiating forms. Its Mohs hardness is 5. 0–6.0, and its gravity is 3. 0–3.4. Cleavage is perfect, two directions in the shape of a diamond, fracture is uneven, splintery and it is often translucent to nearly opaque. It was first described in 1888 for an occurrence on Socotra Island, Aden Governorate, Yemen and it typically forms dark-blue elongated to fibrous crystals in highly alkali granites, syenites, rarely in felsic volcanics, granite pegmatites and schist. It occurs in banded iron formations as the asbestiform variety crocidolite, the riebeckite granite known as ailsite, found on the island of Ailsa Craig in western Scotland, is prized for its use in the manufacture of curling stones. Riebeckite granite was used for the stones of the Canton Viaduct from Moyles Quarry now part of Borderland State Park in Massachusetts. The commonwealths name is taken from an Algonquian word for the Great Blue Hill. The fibrous forms of riebeckite are known as crocidolite and are one of the six recognised types of asbestos, often referred to as blue asbestos, it is considered the most hazardous. In 1964 Dr Christopher Wagner discovered an association between blue asbestos and mesothelioma, Crocidolite asbestos was mined in South Africa, Bolivia and also at Wittenoom, Western Australia. Bolivian crocidolite was used in Kent Micronite cigarette filters in the 1950s, Blue asbestos was also used in early gas masks. In the mid-20th century, asbestos was confirmed to be harmful, List of minerals List of minerals named after people Chisholm, Hugh, ed. Crocidolite
27.
Cummington, Massachusetts
–
Cummington is a town in Hampshire County, Massachusetts, United States. The population was 872 at the 2010 census and it is part of the Springfield, Massachusetts Metropolitan Statistical Area. Cummington was first settled in 1762 and was incorporated in 1779. It was named after Colonel John Cumings, the original landholder, the first Congregational Church minister was Rev. James Briggs of Norton, Massachusetts, and a graduate of Yale College around 1775. Briggs was the son of Deacon James and Damaris Briggs, although a small town, several Revolutionary War patriots are buried there, including Nathaniel Holbrook, Seth Wilder, Sr. and Seth Wilder, Jr. Noted poet and newspaper editor William Cullen Bryant was born in Cummington and his house is now preserved and open to the public as the William Cullen Bryant Homestead. The town hosts the Cummington Fair every August on the towns fairgrounds, the fair features many events including adult and 4-H exhibition halls, a craft barn, vaudeville stage, antique car parade, oxen pull, and an assortment of fair rides, games, and food stands. The town was the subject of a 1945 documentary film, The Cummington Story, according to the United States Census Bureau, the town has a total area of 23.0 square miles, all land. The East Branch of the Westfield River flows through Cummington, the mineral cummingtonite was first found in this town and was named after it. As of the census of 2000, there were 978 people,382 households, the population density was 42.4 people per square mile. There were 452 housing units at a density of 19.6 per square mile. The racial makeup of the town was 96. 42% White,0. 61% African American,0. 41% Native American,0. 31% Asian,0. 51% from other races, hispanic or Latino of any race were 3. 27% of the population. 28. 0% of all households were made up of individuals and 10. 2% had someone living alone who was 65 years of age or older, the average household size was 2.26 and the average family size was 2.77. In the town, the population was out with 27. 9% under the age of 18,5. 7% from 18 to 24,30. 3% from 25 to 44,24. 8% from 45 to 64. The median age was 38 years, for every 100 females there were 102.5 males. For every 100 females age 18 and over, there were 92.1 males, the median income for a household in the town was $42,250, and the median income for a family was $48,750. Males had an income of $31,765 versus $27,279 for females. The per capita income for the town was $21,553, about 4. 2% of families and 6. 6% of the population were below the poverty line, including 5. 7% of those under age 18 and none of those age 65 or over
28.
Sweden
–
Sweden, officially the Kingdom of Sweden, is a Scandinavian country in Northern Europe. It borders Norway to the west and Finland to the east, at 450,295 square kilometres, Sweden is the third-largest country in the European Union by area, with a total population of 10.0 million. Sweden consequently has a low density of 22 inhabitants per square kilometre. Approximately 85% of the lives in urban areas. Germanic peoples have inhabited Sweden since prehistoric times, emerging into history as the Geats/Götar and Swedes/Svear, Southern Sweden is predominantly agricultural, while the north is heavily forested. Sweden is part of the area of Fennoscandia. The climate is in very mild for its northerly latitude due to significant maritime influence. Today, Sweden is a monarchy and parliamentary democracy, with a monarch as head of state. The capital city is Stockholm, which is also the most populous city in the country, legislative power is vested in the 349-member unicameral Riksdag. Executive power is exercised by the government chaired by the prime minister, Sweden is a unitary state, currently divided into 21 counties and 290 municipalities. Sweden emerged as an independent and unified country during the Middle Ages, in the 17th century, it expanded its territories to form the Swedish Empire, which became one of the great powers of Europe until the early 18th century. Swedish territories outside the Scandinavian Peninsula were gradually lost during the 18th and 19th centuries, the last war in which Sweden was directly involved was in 1814, when Norway was militarily forced into personal union. Since then, Sweden has been at peace, maintaining a policy of neutrality in foreign affairs. The union with Norway was peacefully dissolved in 1905, leading to Swedens current borders, though Sweden was formally neutral through both world wars, Sweden engaged in humanitarian efforts, such as taking in refugees from German-occupied Europe. After the end of the Cold War, Sweden joined the European Union on 1 January 1995 and it is also a member of the United Nations, the Nordic Council, Council of Europe, the World Trade Organization and the Organisation for Economic Co-operation and Development. Sweden maintains a Nordic social welfare system that provides health care. The modern name Sweden is derived through back-formation from Old English Swēoþēod and this word is derived from Sweon/Sweonas. The Swedish name Sverige literally means Realm of the Swedes, excluding the Geats in Götaland, the etymology of Swedes, and thus Sweden, is generally not agreed upon but may derive from Proto-Germanic Swihoniz meaning ones own, referring to ones own Germanic tribe
29.
South Africa
–
South Africa, officially the Republic of South Africa, is the southernmost country in Africa. South Africa is the 25th-largest country in the world by land area and it is the southernmost country on the mainland of the Old World or the Eastern Hemisphere. About 80 percent of South Africans are of Sub-Saharan African ancestry, divided among a variety of ethnic groups speaking different Bantu languages, the remaining population consists of Africas largest communities of European, Asian, and multiracial ancestry. South Africa is a multiethnic society encompassing a variety of cultures, languages. Its pluralistic makeup is reflected in the recognition of 11 official languages. The country is one of the few in Africa never to have had a coup détat, however, the vast majority of black South Africans were not enfranchised until 1994. During the 20th century, the black majority sought to recover its rights from the dominant white minority, with this struggle playing a role in the countrys recent history. The National Party imposed apartheid in 1948, institutionalising previous racial segregation, since 1994, all ethnic and linguistic groups have held political representation in the countrys democracy, which comprises a parliamentary republic and nine provinces. South Africa is often referred to as the Rainbow Nation to describe the multicultural diversity. The World Bank classifies South Africa as an economy. Its economy is the second-largest in Africa, and the 34th-largest in the world, in terms of purchasing power parity, South Africa has the seventh-highest per capita income in Africa. However, poverty and inequality remain widespread, with about a quarter of the population unemployed, nevertheless, South Africa has been identified as a middle power in international affairs, and maintains significant regional influence. The name South Africa is derived from the geographic location at the southern tip of Africa. Upon formation the country was named the Union of South Africa in English, since 1961 the long form name in English has been the Republic of South Africa. In Dutch the country was named Republiek van Zuid-Afrika, replaced in 1983 by the Afrikaans Republiek van Suid-Afrika, since 1994 the Republic has had an official name in each of its 11 official languages. Mzansi, derived from the Xhosa noun umzantsi meaning south, is a name for South Africa. South Africa contains some of the oldest archaeological and human fossil sites in the world, extensive fossil remains have been recovered from a series of caves in Gauteng Province. The area is a UNESCO World Heritage site and has termed the Cradle of Humankind
30.
Scotland
–
Scotland is a country that is part of the United Kingdom and covers the northern third of the island of Great Britain. It shares a border with England to the south, and is surrounded by the Atlantic Ocean, with the North Sea to the east. In addition to the mainland, the country is made up of more than 790 islands, including the Northern Isles, the Kingdom of Scotland emerged as an independent sovereign state in the Early Middle Ages and continued to exist until 1707. By inheritance in 1603, James VI, King of Scots, became King of England and King of Ireland, Scotland subsequently entered into a political union with the Kingdom of England on 1 May 1707 to create the new Kingdom of Great Britain. The union also created a new Parliament of Great Britain, which succeeded both the Parliament of Scotland and the Parliament of England. Within Scotland, the monarchy of the United Kingdom has continued to use a variety of styles, titles, the legal system within Scotland has also remained separate from those of England and Wales and Northern Ireland, Scotland constitutes a distinct jurisdiction in both public and private law. Glasgow, Scotlands largest city, was one of the worlds leading industrial cities. Other major urban areas are Aberdeen and Dundee, Scottish waters consist of a large sector of the North Atlantic and the North Sea, containing the largest oil reserves in the European Union. This has given Aberdeen, the third-largest city in Scotland, the title of Europes oil capital, following a referendum in 1997, a Scottish Parliament was re-established, in the form of a devolved unicameral legislature comprising 129 members, having authority over many areas of domestic policy. Scotland is represented in the UK Parliament by 59 MPs and in the European Parliament by 6 MEPs, Scotland is also a member nation of the British–Irish Council, and the British–Irish Parliamentary Assembly. Scotland comes from Scoti, the Latin name for the Gaels, the Late Latin word Scotia was initially used to refer to Ireland. By the 11th century at the latest, Scotia was being used to refer to Scotland north of the River Forth, alongside Albania or Albany, the use of the words Scots and Scotland to encompass all of what is now Scotland became common in the Late Middle Ages. Repeated glaciations, which covered the land mass of modern Scotland. It is believed the first post-glacial groups of hunter-gatherers arrived in Scotland around 12,800 years ago, the groups of settlers began building the first known permanent houses on Scottish soil around 9,500 years ago, and the first villages around 6,000 years ago. The well-preserved village of Skara Brae on the mainland of Orkney dates from this period and it contains the remains of an early Bronze Age ruler laid out on white quartz pebbles and birch bark. It was also discovered for the first time that early Bronze Age people placed flowers in their graves, in the winter of 1850, a severe storm hit Scotland, causing widespread damage and over 200 deaths. In the Bay of Skaill, the storm stripped the earth from a large irregular knoll, when the storm cleared, local villagers found the outline of a village, consisting of a number of small houses without roofs. William Watt of Skaill, the laird, began an amateur excavation of the site, but after uncovering four houses
31.
New Zealand
–
New Zealand /njuːˈziːlənd/ is an island nation in the southwestern Pacific Ocean. The country geographically comprises two main landmasses—the North Island, or Te Ika-a-Māui, and the South Island, or Te Waipounamu—and around 600 smaller islands. New Zealand is situated some 1,500 kilometres east of Australia across the Tasman Sea and roughly 1,000 kilometres south of the Pacific island areas of New Caledonia, Fiji, because of its remoteness, it was one of the last lands to be settled by humans. During its long period of isolation, New Zealand developed a distinct biodiversity of animal, fungal, the countrys varied topography and its sharp mountain peaks, such as the Southern Alps, owe much to the tectonic uplift of land and volcanic eruptions. New Zealands capital city is Wellington, while its most populous city is Auckland, sometime between 1250 and 1300 CE, Polynesians settled in the islands that later were named New Zealand and developed a distinctive Māori culture. In 1642, Dutch explorer Abel Tasman became the first European to sight New Zealand, in 1840, representatives of Britain and Māori chiefs signed the Treaty of Waitangi, which declared British sovereignty over the islands. In 1841, New Zealand became a colony within the British Empire, today, the majority of New Zealands population of 4.7 million is of European descent, the indigenous Māori are the largest minority, followed by Asians and Pacific Islanders. Reflecting this, New Zealands culture is derived from Māori and early British settlers. The official languages are English, Māori and New Zealand Sign Language, New Zealand is a developed country and ranks highly in international comparisons of national performance, such as health, education, economic freedom and quality of life. Since the 1980s, New Zealand has transformed from an agrarian, Queen Elizabeth II is the countrys head of state and is represented by a governor-general. In addition, New Zealand is organised into 11 regional councils and 67 territorial authorities for local government purposes, the Realm of New Zealand also includes Tokelau, the Cook Islands and Niue, and the Ross Dependency, which is New Zealands territorial claim in Antarctica. New Zealand is a member of the United Nations, Commonwealth of Nations, ANZUS, Organisation for Economic Co-operation and Development, Pacific Islands Forum, and Asia-Pacific Economic Cooperation. Dutch explorer Abel Tasman sighted New Zealand in 1642 and called it Staten Landt, in 1645, Dutch cartographers renamed the land Nova Zeelandia after the Dutch province of Zeeland. British explorer James Cook subsequently anglicised the name to New Zealand, Aotearoa is the current Māori name for New Zealand. It is unknown whether Māori had a name for the country before the arrival of Europeans. Māori had several names for the two main islands, including Te Ika-a-Māui for the North Island and Te Waipounamu or Te Waka o Aoraki for the South Island. Early European maps labelled the islands North, Middle and South, in 1830, maps began to use North and South to distinguish the two largest islands and by 1907, this was the accepted norm. The New Zealand Geographic Board discovered in 2009 that the names of the North Island and South Island had never been formalised and this set the names as North Island or Te Ika-a-Māui, and South Island or Te Waipounamu
32.
Grunerite
–
Grunerite is a mineral of the amphibole group of minerals with formula Fe7Si8O222. It is the iron endmember of the grunerite-cummingtonite series and it forms as fibrous, columnar or massive aggregates of crystals. The luster is glassy to pearly with colors ranging from green, the Mohs hardness is 5 to 6 and the specific gravity is 3.4 to 3.5. It was discovered in 1853 and named after Emmanuel-Louis Gruner, a Swiss-French chemist who first analysed it, amosite is a rare asbestiform variety of grunerite that was mined as asbestos predominantly in the eastern part of the Transvaal Province of South Africa. The origin of the name is Amosa, the acronym for the mining company Asbestos Mines of South Africa
33.
Solid solution
–
A solid solution is a solid-state solution of one or more solutes in a solvent. The solid solution needs to be distinguished from a mechanical mixtures of powdered solids like two salts, sugar and salt, etc, the mechanical mixtures have total or partial miscibility gap in solid state. Examples of solid solutions include crystallized salts from their liquid mixture, metal alloys, in the case of metal alloys intermetallic compounds occur frequently. The solute may incorporate into the solvent crystal lattice substitutionally, by replacing a solvent particle in the lattice, or interstitially, by fitting into the space between solvent particles. Both of these types of solid solution affect the properties of the material by distorting the crystal lattice, some mixtures will readily form solid solutions over a range of concentrations, while other mixtures will not form solid solutions at all. The propensity for any two substances to form a solution is a complicated matter involving the chemical, crystallographic. 1 displays an alloy of two metals which forms a solution at all relative concentrations of the two species. Solid solutions have important commercial and industrial applications, as such mixtures often have superior properties to pure materials, many metal alloys are solid solutions. Even small amounts of solute can affect the electrical and physical properties of the solvent, the binary phase diagram in Fig.2 shows the phases of a mixture of two substances in varying concentrations, A and B. The region labeled α is a solution, with B acting as the solute in a matrix of A. On the other end of the scale, the region labeled β is also a solid solution. The large solid region in between the α and β solid solutions, labeled α + β, is not a solid solution, at other proportions, the material will enter a mushy or pasty phase until it warms up to being completely melted. The mixture at the dip point of the diagram is called a eutectic alloy, lead-tin mixtures formulated at that point are useful when soldering electronic components, particularly if done manually, since the solid phase is quickly entered as the solder cools. In contrast, when lead-tin mixtures were used to solder seams in automobile bodies a pasty state enabled a shape to be formed with a paddle or tool. When a solid solution becomes unstable — due to a temperature, for example — exsolution occurs. This is mainly caused by difference in cation size, cations which have a large difference in radii are not likely to readily substitute. Take the alkali feldspar minerals for example, whose end members are albite, NaAlSi3O8 and microcline and this leads to exsolution where they will separate into two separate phases. In the case of the feldspar minerals, thin white albite layers will alternate between typically pink microcline
34.
Manganese
–
Manganese is a chemical element with symbol Mn and atomic number 25. It is not found as an element in nature, it is often found in minerals in combination with iron. Manganese is a metal with important industrial metal alloy uses, particularly in stainless steels, by the mid-18th century, Swedish chemist Carl Wilhelm Scheele had used pyrolusite to produce chlorine. Scheele and others were aware that pyrolusite contained a new element, johan Gottlieb Gahn was the first to isolate an impure sample of manganese metal in 1774, which he did by reducing the dioxide with carbon. Manganese phosphating is used for rust and corrosion prevention on steel, ionized manganese is used industrially as pigments of various colors, which depend on the oxidation state of the ions. The permanganates of alkali and alkaline earth metals are powerful oxidizers, Manganese dioxide is used as the cathode material in zinc-carbon and alkaline batteries. In biology, manganese ions function as cofactors for a variety of enzymes with many functions. Manganese enzymes are essential in detoxification of superoxide free radicals in organisms that must deal with elemental oxygen. Manganese also functions in the complex of photosynthetic plants. The element is a trace mineral for all known living organisms but is a neurotoxin. In larger amounts, and apparently with far greater effectiveness through inhalation, Manganese is a silvery-gray metal that resembles iron. It is hard and very brittle, difficult to fuse, Manganese metal and its common ions are paramagnetic. Manganese tarnishes slowly in air and oxidizes like iron in water containing dissolved oxygen, naturally occurring manganese is composed of one stable isotope, 55Mn. Eighteen radioisotopes have been isolated and described, the most stable being 53Mn with a half-life of 3.7 million years, 54Mn with a half-life of 312.3 days, and 52Mn with a half-life of 5.591 days. All of the radioactive isotopes have half-lives of less than three hours, and the majority of less than one minute. Manganese also has three meta states, Manganese is part of the iron group of elements, which are thought to be synthesized in large stars shortly before the supernova explosion. 53Mn decays to 53Cr with a half-life of 3.7 million years, because of its relatively short half-life, 53Mn is relatively rare, produced by cosmic rays impact on iron. Manganese isotopic contents are combined with chromium isotopic contents and have found application in isotope geology
35.
Banded iron formation
–
Banded iron formations are distinctive units of sedimentary rock that are almost always of Precambrian age. Some of the oldest known rock formations, formed over 3,700 million years ago, Banded layers rich in iron were mostly deposited between 2,400 and 1,900 mya. Phanerozoic ironstones generally have a different genesis, Banded iron beds are an important commercial source of iron ore, such as the Pilbara region of Western Australia and the Animikie Group in Minnesota. The formations are abundant around the time of the great event,2,400 million years ago. The conventional concept is that the banded iron layers were formed in sea water as the result of oxygen released by photosynthetic cyanobacteria. The oxygen then combined with dissolved iron in Earths oceans to form insoluble iron oxides, which precipitated out, forming a layer on the ocean floor. Each band is similar to a varve, to the extent that the banding is assumed to result from variations in available oxygen. It is unclear whether these banded ironstone formations were seasonal, followed some feedback oscillation in the complex system or followed some other cycle. It is assumed that initially the Earth started with vast amounts of iron, as photosynthetic organisms generated oxygen, the available iron in the Earths oceans precipitated out as iron oxides. An alternative explanation of these deposits has undergone much discussion as part of the Snowball Earth hypothesis. Several hypotheses exist for the initiation of the Snowball Earths, in a Snowball Earth state the earths continents, and possibly seas at low latitudes, were subject to an ice age. If this was the case, Earths free oxygen may have nearly or totally depleted during a severe ice age circa 750 to 580 million years ago. Dissolved iron then accumulated in the oxygen-poor oceans, following the thawing of the Earth, the seas became oxygenated once more causing the precipitation of the iron. Another mechanism for BIFs, also proposed in the context of the Snowball Earth discussion, is by deposition from metal-rich brines in the vicinity of hydrothermally active rift zones, alternatively, some geochemists suggest that BIFs could form by direct oxidation of iron by microbial anoxygenic phototrophs. Northern Minnesotas banded iron formations lie directly underneath a layer of material only recently recognized as ejecta from the Sudbury Basin impact. At the time of formation Earth had a single supercontinent called Columbia with substantial continental shelves, an asteroid slammed into waters about 1,000 m deep some 1.85 billion years ago. Computer models suggest that the tsunami would have been at least 1,000 m at the epicentre and those immense waves and large underwater landslides triggered by the impact stirred the ocean, bringing oxygenated waters from the surface down to the ocean floor. Sediments deposited on the seafloor before the impact, including BIFs contained little if any oxidized iron and this Fe to Fe ratio suggests that most parts of the ocean were relatively devoid of oxygen
36.
Calcium
–
Calcium is a chemical element with symbol Ca and atomic number 20. Calcium is a soft grayish-yellow alkaline earth metal, fifth-most-abundant element by mass in the Earths crust, the ion Ca2+ is also the fifth-most-abundant dissolved ion in seawater by both molarity and mass, after sodium, chloride, magnesium, and sulfate. Free calcium metal is too reactive to occur in nature, Calcium is produced in supernova nucleosynthesis. Calcium is a trace element in living organisms. It is the most abundant metal by mass in animals, and it is an important constituent of bone, teeth. In cell biology, the movement of the calcium ion into, Calcium carbonate and calcium citrate are often taken as dietary supplements. Calcium is on the World Health Organizations List of Essential Medicines, Calcium has a wide variety of applications, almost all of which are associated with calcium compounds and salts. Calcium metal is used as a deoxidizer, desulfurizer, and decarbonizer for production of ferrous and nonferrous alloys. In steelmaking and production of iron, Ca reacts with oxygen, Calcium carbonate is used in manufacturing cement and mortar, lime, limestone and aids in production in the glass industry. It also has chemical and optical uses as mineral specimens in toothpastes, Calcium hydroxide solution is used to detect the presence of carbon dioxide in a gas sample bubbled through a solution. The solution turns cloudy where CO2 is present, Calcium arsenate is used in insecticides. Calcium carbide is used to make acetylene gas and various plastics, Calcium chloride is used in ice removal and dust control on dirt roads, as a conditioner for concrete, as an additive in canned tomatoes, and to provide body for automobile tires. Calcium citrate is used as a food preservative, Calcium cyclamate is used as a sweetening agent in several countries. In the United States, it has been outlawed as a suspected carcinogen, Calcium gluconate is used as a food additive and in vitamin pills. Calcium hypochlorite is used as a swimming pool disinfectant, as an agent, as an ingredient in deodorant. Calcium permanganate is used in rocket propellant, textile production, as a water sterilizing agent. Calcium phosphate is used as a supplement for animal feed, fertilizer, in production for dough and yeast products, in the manufacture of glass. Calcium phosphide is used in fireworks, rodenticide, torpedoes, Calcium sulfate is used as common blackboard chalk, as well as, in its hemihydrate form, Plaster of Paris
37.
Sodium
–
Sodium is a chemical element with symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal, Sodium is an alkali metal, being in group 1 of the periodic table, because it has a single electron in its outer shell that it readily donates, creating a positively charged atom—the Na+ cation. Its only stable isotope is 23Na, the free metal does not occur in nature, but must be prepared from compounds. Sodium is the sixth most abundant element in the Earths crust, Sodium was first isolated by Humphry Davy in 1807 by the electrolysis of sodium hydroxide. Among many other useful compounds, sodium hydroxide is used in soap manufacture, and sodium chloride is a de-icing agent. Sodium is an element for all animals and some plants. Sodium ions are the major cation in the fluid and as such are the major contributor to the ECF osmotic pressure. Loss of water from the ECF compartment increases the sodium concentration, isotonic loss of water and sodium from the ECF compartment decreases the size of that compartment in a condition called ECF hypovolemia. In nerve cells, the charge across the cell membrane enables transmission of the nerve impulse—an action potential—when the charge is dissipated. The melting and boiling points of sodium are lower than those of lithium but higher than those of the alkali metals potassium, rubidium. All of these high-pressure allotropes are insulators and electrides.3 nm, spin-orbit interactions involving the electron in the 3p orbital split the D line into two, at 589.0 and 589.6 nm, hyperfine structures involving both orbitals cause many more lines. Twenty isotopes of sodium are known, but only 23Na is stable, 23Na is created in the carbon-burning process in stars by fusing two carbon atoms together, this requires temperatures above 600 megakelvins and a star of at least three solar masses. Two nuclear isomers have been discovered, the one being 24mNa with a half-life of around 20.2 milliseconds. Sodium atoms have 11 electrons, one more than the stable configuration of the noble gas neon. This process requires so little energy that sodium is oxidized by giving up its 11th electron. In contrast, the ionization energy is very high, because the 10th electron is closer to the nucleus than the 11th electron. As a result, sodium usually forms ionic compounds involving the Na+ cation, the most common oxidation state for sodium is +1. It is generally less reactive than potassium and more reactive than lithium, Sodium metal is highly reducing, with the reduction of sodium ions requiring −2.71 volts, though potassium and lithium have even more negative potentials
38.
Potassium
–
Potassium is a chemical element with symbol K and atomic number 19. It was first isolated from potash, the ashes of plants, in the periodic table, potassium is one of the alkali metals. Potassium in nature only in ionic salts. It is found dissolved in sea water, and is part of many minerals, naturally occurring potassium is composed of three isotopes, of which 40K is radioactive. Traces of 40K are found in all potassium, and it is the most common radioisotope in the human body, Potassium is chemically very similar to sodium, the previous element in Group 1 of the periodic table. They have a similar energy, which allows for each atom to give up its sole outer electron. That they are different elements combine with the same anions to make similar salts was suspected in 1702. Most industrial applications of potassium exploit the high solubility in water of potassium compounds, heavy crop production rapidly depletes the soil of potassium, and this can be remedied with agricultural fertilizers containing potassium, accounting for 95% of global potassium chemical production. Potassium ions are necessary for the function of all living cells, fresh fruits and vegetables are good dietary sources of potassium. Potassium is the second least dense metal after lithium and it is a soft solid with a low melting point, and can be easily cut with a knife. Freshly cut potassium is silvery in appearance, but it begins to tarnish toward gray immediately on exposure to air, in a flame test, potassium and its compounds emit a lilac color with a peak emission wavelength of 766.5 nanometers. Neutral potassium atoms have 19 electrons, one more than the stable configuration of the noble gas argon. This process requires so little energy that potassium is readily oxidized by atmospheric oxygen, in contrast, the second ionization energy is very high, because removal of two electrons breaks the stable noble gas electronic configuration. Potassium therefore does not readily form compounds with the state of +2 or higher. Potassium is an active metal that reacts violently with oxygen in water. With oxygen it forms potassium peroxide, and with water potassium forms potassium hydroxide, the reaction of potassium with water is dangerous because of its violent exothermic character and the production of hydrogen gas. Hydrogen reacts again with atmospheric oxygen, producing water, which reacts with the remaining potassium and this reaction requires only traces of water, because of this, potassium and the liquid sodium-potassium — NaK — are potent desiccants that can be used to dry solvents prior to distillation. Because of the sensitivity of potassium to water and air, reactions with other elements are only in an inert atmosphere such as argon gas using air-free techniques
39.
Ferric
–
Ferric refers to iron-containing materials or compounds. In chemistry the term is reserved for iron with an number of +3. On the other hand, ferrous refers to iron with oxidation number of +2, iron is usually the most stable form of iron in air, as illustrated by the pervasiveness of rust, an insoluble iron-containing material. The word ferric is derived from the Latin word ferrum for iron, examples include iron-sulfur clusters, oxyhemoglobin, ferritin, and the cytochromes. The bioavailability of iron is of great interest because all forms of life require iron. Iron-deficiency anemia illustrates the problems resulting from low iron intake, many foods contain soluble iron compounds and are therefore necessary for good nutrition. The low bioavailability of iron affects all forms of life, bacteria secrete iron-attracting agents called siderophores that form soluble compounds of iron that can be reabsorbed into the cell and used in building iron-containing metalloproteins. The impact of increasing the bioavailability of iron was famously demonstrated by an experiment where an area of the ocean surface was sprayed with iron salts. After several days, the phytoplankton within the treated area bloomed to such an extent that the effect was visible from outer space and this fertilizing process has been proposed as a means to mitigate the carbon dioxide content of the atmosphere. Ferric iron mitigates the eutrophication of lakes by reducing the bioavailability of phosphorus in the water, mitigation arises because ferric phosphate is insoluble. Like iron, phosphate is often a limiting nutrient, and its reduction in concentration from solution limits the growth of algae, in water, ferric iron forms compounds that are often insoluble, at least near neutral pH. A salt of ferric iron hydrolyzes water and produces iron oxide-hydroxides while contributing hydrogen ions to the solution, in contrast, typical Na+ salts dissolve in water without lowering the pH. Aluminium behaves similarly to ferric ion, rust, a mixture of ferric hydroxide compounds, illustrates the low solubility of ferric ions in water. Various reagents cause rust to dissolve even at neutral pH and these ligands include EDTA, which forms a chelate complex with the ion, displacing the hydroxide and oxide ligands that comprise rust. For this reason, EDTA is often used to iron deposits or to deliver soluble iron in fertilizers. Citrate also solubilizes ferric ion at neutral pH, although its complexes are less stable than those of EDTA, Ferric iron is a d5 center, meaning that the metal has five valence electrons in the 3d orbital shell. The magnetism of ferric compounds is determined by these five electrons. Usually ferric ions are surrounded by six ligands arranged in octahedron, sometimes three and sometimes as many as seven ligands are observed
40.
Aluminium
–
Aluminium or aluminum is a chemical element in the boron group with symbol Al and atomic number 13. It is a silvery-white, soft, nonmagnetic, ductile metal, Aluminium metal is so chemically reactive that native specimens are rare and limited to extreme reducing environments. Instead, it is combined in over 270 different minerals. The chief ore of aluminium is bauxite, Aluminium is remarkable for the metals low density and its ability to resist corrosion through the phenomenon of passivation. Aluminium and its alloys are vital to the industry and important in transportation and structures, such as building facades. The oxides and sulfates are the most useful compounds of aluminium, despite its prevalence in the environment, no known form of life uses aluminium salts metabolically, but aluminium is well tolerated by plants and animals. Because of these salts abundance, the potential for a role for them is of continuing interest. Aluminium is a soft, durable, lightweight, ductile. It is nonmagnetic and does not easily ignite, a fresh film of aluminium serves as a good reflector of visible light and an excellent reflector of medium and far infrared radiation. The yield strength of aluminium is 7–11 MPa, while aluminium alloys have yield strengths ranging from 200 MPa to 600 MPa. Aluminium has about one-third the density and stiffness of steel and it is easily machined, cast, drawn and extruded. Aluminium atoms are arranged in a cubic structure. Aluminium has an energy of approximately 200 mJ/m2. Aluminium is a thermal and electrical conductor, having 59% the conductivity of copper. Aluminium is capable of superconductivity, with a critical temperature of 1.2 kelvin. Aluminium is the most common material for the fabrication of superconducting qubits, the strongest aluminium alloys are less corrosion resistant due to galvanic reactions with alloyed copper. This corrosion resistance is reduced by aqueous salts, particularly in the presence of dissimilar metals. In highly acidic solutions, aluminium reacts with water to form hydrogen, primarily because it is corroded by dissolved chlorides, such as common sodium chloride, household plumbing is never made from aluminium
41.
Amosite
–
Grunerite is a mineral of the amphibole group of minerals with formula Fe7Si8O222. It is the iron endmember of the grunerite-cummingtonite series and it forms as fibrous, columnar or massive aggregates of crystals. The luster is glassy to pearly with colors ranging from green, the Mohs hardness is 5 to 6 and the specific gravity is 3.4 to 3.5. It was discovered in 1853 and named after Emmanuel-Louis Gruner, a Swiss-French chemist who first analysed it, amosite is a rare asbestiform variety of grunerite that was mined as asbestos predominantly in the eastern part of the Transvaal Province of South Africa. The origin of the name is Amosa, the acronym for the mining company Asbestos Mines of South Africa
42.
Asbestos
–
They are commonly known by their colors, as blue asbestos, brown asbestos, white asbestos, and green asbestos. It was used in applications as electrical insulation for hotplate wiring. When asbestos is used for its resistance to fire or heat and these desirable properties made asbestos very widely used. Prolonged inhalation of asbestos fibers can cause serious and fatal illnesses including cancer, mesothelioma. Concern of asbestos-related illness in modern times began in the 20th century, by the 1980s and 1990s, asbestos trade and use were heavily restricted, phased out, or banned outright in an increasing number of countries. S. History and a much lesser legal issue in most other countries involved, asbestos-related liability also remains an ongoing concern for many manufacturers, insurers and reinsurers. Asbestos derives from the ancient Greek ἄσβεστος, meaning unquenchable or inextinguishable, the word is pronounced /æsˈbɛstəs/, /æzˈbɛstəs/ or /æzˈbɛstɒs/. Six mineral types are defined by the United States Environmental Protection Agency as asbestos including those belonging to the serpentine class, all six asbestos mineral types are known to be human carcinogens. The visible fibers are themselves composed of millions of microscopic fibrils that can be released by abrasion. Chrysotile is the member of the serpentine class. 12001-29-5, is obtained from rocks which are common throughout the world. Its idealized chemical formula is Mg34, chrysotile appears under the microscope as a white fiber. Chrysotile has been used more than any type and accounts for about 95% of the asbestos found in buildings in America. Chrysotile is more flexible than amphibole types of asbestos, and can be spun, the most common use was corrugated asbestos cement roofing primarily for outbuildings, warehouses and garages. It may also be found in sheets or panels used for ceilings and sometimes for walls, chrysotile has been a component in joint compound and some plasters. Amosite, crocidolite, tremolite, anthophyllite and actinolite are members of the amphibole class, one formula given for amosite is Fe7Si8O222. Amosite is seen under a microscope as a grey-white vitreous fiber and it is found most frequently as a fire retardant in thermal insulation products, asbestos insulating board and ceiling tiles. 12001-28-4, is the form of the amphibole riebeckite, found primarily in southern Africa
43.
Transvaal Province
–
The Province of the Transvaal, commonly referred to as the Transvaal Province was a province of South Africa from 1910 until the end of apartheid in 1994, when a new constitution subdivided it. The name Transvaal refers to the geographical location to the north of the Vaal River. Its capital was Pretoria, which was also the countrys, in 1910, four British colonies united to form the Union of South Africa. The Transvaal Colony, which had formed out of the bulk of the old South African Republic after the Second Boer War. Half a century later, in 1961, the union ceased to be part of the Commonwealth of Nations, the PWV conurbation in the Transvaal, centered on Pretoria and Johannesburg, became South Africas economic powerhouse, a position it still holds today as Gauteng province. In 1994, after the fall of apartheid, the provinces were restructured. The south-central portion became Gauteng, the northern portion became Limpopo, most of the North West came from the southwestern portion of the old Transvaal, and tiny segment of the Transvaal joined KwaZulu-Natal. Except on the south-west, these borders were mostly defined by natural features. Several Bantustans were entirely inside the Transvaal, Venda, KwaNdebele, Gazankulu, KaNgwane, parts of Bophuthatswana were also in the Transvaal, with other parts in Cape Province and Orange Free State. Within the Transvaal lies the Waterberg Massif, a prominent ancient geological feature of the South African landscape, districts of the province and population at the 1991 census
44.
Hornblende
–
Hornblende is a complex inosilicate series of minerals. It is not a mineral in its own right, but the name is used as a general or field term. Hornblende is a mixture of three molecules, a calcium-iron-magnesium silicate, an aluminium-iron-magnesium silicate, and an iron-magnesium silicate. The general formula can be given as 2–358O222, some metals vary in their occurrence and magnitude, Manganese and titanium are often present. Sodium and potassium are present and fluorine often substitutes for the hydroxyl in the crystalline structure. Hornblende has a hardness of 5–6, a gravity of 2. 9–3.4 and is typically an opaque green. Its cleavage angles are at 56 and 124 degrees and it is most often confused with various pyroxene minerals and biotite mica, which are black and can be found in granite and in charnockite. Hornblende is a constituent of many igneous and metamorphic rocks such as granite, syenite, diorite, gabbro, basalt, andesite, gneiss. It is the mineral of amphibolites. Very dark brown to black hornblendes that contain titanium are ordinarily called basaltic hornblende, from the fact that they are usually a constituent of basalt, hornblende alters easily to chlorite and epidote. A rare variety of hornblende contains less than 5% of iron oxide, is gray to white in color, and named edenite, from its locality in Edenville, Orange County, New York. List of minerals Hurlbut, Cornelius S. Klein, Cornelis,1985, Manual of Mineralogy, 20th ed. John Wiley and Sons, New York, p 416-7, ISBN 0-471-80580-7 Scandinavian mineral gallery retrieved 06/21/05
