1.
Metamorphic rock
–
Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means change in form. The original rock is subjected to heat and pressure, causing profound physical and/or chemical change, the protolith may be a sedimentary, an igneous, or even an existing type of metamorphic rock. Metamorphic rocks make up a part of the Earths crust. They are classified by texture and by chemical and mineral assemblage and they may be formed simply by being deep beneath the Earths surface, subjected to high temperatures and the great pressure of the rock layers above it. They can form from tectonic processes such as continental collisions, which cause horizontal pressure and they are also formed when rock is heated up by the intrusion of hot molten rock called magma from the Earths interior. The study of rocks provides information about the temperatures and pressures that occur at great depths within the Earths crust. Some examples of rocks are gneiss, slate, marble, schist. Metamorphic minerals are those that only at the high temperatures and pressures associated with the process of metamorphism. These minerals, known as index minerals, include sillimanite, kyanite, staurolite, andalusite, and some garnet. Other minerals, such as olivines, pyroxenes, amphiboles, micas, feldspars, and quartz, may be found in metamorphic rocks and these minerals formed during the crystallization of igneous rocks. They are stable at temperatures and pressures and may remain chemically unchanged during the metamorphic process. However, all minerals are only within certain limits. The change in the size of the rock during the process of metamorphism is called recrystallization. Both high temperatures and pressures contribute to recrystallization, high temperatures allow the atoms and ions in solid crystals to migrate, thus reorganizing the crystals, while high pressures cause solution of the crystals within the rock at their point of contact. The layering within metamorphic rocks is called foliation, and it occurs when a rock is being shortened along one axis during recrystallization. This causes the platy or elongated crystals of minerals, such as mica and chlorite and this results in a banded, or foliated rock, with the bands showing the colors of the minerals that formed them. Textures are separated into foliated and non-foliated categories, foliated rock is a product of differential stress that deforms the rock in one plane, sometimes creating a plane of cleavage. For example, slate is a metamorphic rock, originating from shale
Metamorphic rock
–
Quartzite, a form of metamorphic rock, from the Museum of Geology at
University of Tartu collection.
Metamorphic rock
–
Folded foliation in a metamorphic rock from near
Geirangerfjord,
Norway
Metamorphic rock
Metamorphic rock
–
"Metamorphic" redirects here. For other uses, see
Metamorphic (disambiguation).
2.
Chemical formula
–
These are limited to a single typographic line of symbols, which may include subscripts and superscripts. A chemical formula is not a name, and it contains no words. Although a chemical formula may imply certain simple chemical structures, it is not the same as a full chemical structural formula. Chemical formulas can fully specify the structure of only the simplest of molecules and chemical substances, the simplest types of chemical formulas are called empirical formulas, which use letters and numbers indicating the numerical proportions of atoms of each type. Molecular formulas indicate the numbers of each type of atom in a molecule. For example, the formula for glucose is CH2O, while its molecular formula is C6H12O6. This is possible if the relevant bonding is easy to show in one dimension, an example is the condensed molecular/chemical formula for ethanol, which is CH3-CH2-OH or CH3CH2OH. For reasons of structural complexity, there is no condensed chemical formula that specifies glucose, chemical formulas may be used in chemical equations to describe chemical reactions and other chemical transformations, such as the dissolving of ionic compounds into solution. A chemical formula identifies each constituent element by its chemical symbol, in empirical formulas, these proportions begin with a key element and then assign numbers of atoms of the other elements in the compound, as ratios to the key element. For molecular compounds, these numbers can all be expressed as whole numbers. For example, the formula of ethanol may be written C2H6O because the molecules of ethanol all contain two carbon atoms, six hydrogen atoms, and one oxygen atom. Some types of compounds, however, cannot be written with entirely whole-number empirical formulas. An example is boron carbide, whose formula of CBn is a variable non-whole number ratio with n ranging from over 4 to more than 6.5. When the chemical compound of the consists of simple molecules. These types of formulas are known as molecular formulas and condensed formulas. A molecular formula enumerates the number of atoms to reflect those in the molecule, so that the formula for glucose is C6H12O6 rather than the glucose empirical formula. However, except for very simple substances, molecular chemical formulas lack needed structural information, for simple molecules, a condensed formula is a type of chemical formula that may fully imply a correct structural formula. For example, ethanol may be represented by the chemical formula CH3CH2OH
Chemical formula
–
Al 2 (SO 4) 3
3.
Lazurite
–
Lazurite is a tectosilicate mineral with sulfate, sulfur and chloride with formula,8. It is a feldspathoid and a member of the sodalite group, lazurite crystallizes in the isometric system although well formed crystals are rare. It is usually massive and forms the bulk of the lapis lazuli. Lazurite is a blue to greenish blue. The colour is due to the presence of S−3 anions and it has a Mohs hardness of 5.0 to 5.5 and a specific gravity of 2.4. It is translucent with an index of 1.50. It is fusible at 3.5 and soluble in HCl and it commonly contains or is associated with grains of pyrite. Lazurite is a product of metamorphism of limestone and typically is associated with calcite, pyrite, diopside, humite, forsterite, hauyne. Other blue minerals such as the carbonate azurite and the phosphate lazulite may be confused with lazurite, lazurite at one time was used as a synonym for azurite. Lazurite was first described in 1890 for an occurrence in the Sar-e-Sang District, Koksha Valley, Badakhshan Province and it has been mined for over 6,000 years in the lapis lazuli district of Badakhshan, Afghanistan. It has been used as a pigment in painting and cloth dyeing since at least the sixth or seventh century CE and it is also mined at Lake Baikal in Siberia, Mount Vesuvius, Burma, Canada, and the United States. The name is from the Persian lazward for blue, lazurite and hauyne seem to have the same structure and both are sulfate-dominant minerals. Lazurite is a pigment and has a blue streak. Many hauynes have a pale blue streak and are translucent. The difference might be a consequence of the redox state
Lazurite
–
Lazurite, Ladjuar Medam (Lajur Madan; Lapis-lazuli Mine), Sar-e-Sang District, Koksha Valley (Kokscha; Kokcha), Badakhshan (Badakshan; Badahsan) Province, Afghanistan
4.
Crystal system
–
In crystallography, the terms crystal system, crystal family and lattice system each refer to one of several classes of space groups, lattices, point groups or crystals. Informally, two crystals are in the crystal system if they have similar symmetries, though there are many exceptions to this. Space groups and crystals are divided into seven crystal systems according to their point groups, five of the crystal systems are essentially the same as five of the lattice systems, but the hexagonal and trigonal crystal systems differ from the hexagonal and rhombohedral lattice systems. The six crystal families are formed by combining the hexagonal and trigonal crystal systems into one hexagonal family, a lattice system is a class of lattices with the same set of lattice point groups, which are subgroups of the arithmetic crystal classes. The 14 Bravais lattices are grouped into seven lattice systems, triclinic, monoclinic, orthorhombic, tetragonal, rhombohedral, hexagonal, in a crystal system, a set of point groups and their corresponding space groups are assigned to a lattice system. Of the 32 point groups that exist in three dimensions, most are assigned to only one system, in which case both the crystal and lattice systems have the same name. However, five point groups are assigned to two systems, rhombohedral and hexagonal, because both exhibit threefold rotational symmetry. These point groups are assigned to the crystal system. In total there are seven crystal systems, triclinic, monoclinic, orthorhombic, tetragonal, trigonal, hexagonal, a crystal family is determined by lattices and point groups. It is formed by combining crystal systems which have space groups assigned to a lattice system. In three dimensions, the families and systems are identical, except the hexagonal and trigonal crystal systems. In total there are six families, triclinic, monoclinic, orthorhombic, tetragonal, hexagonal. Spaces with less than three dimensions have the number of crystal systems, crystal families and lattice systems. In one-dimensional space, there is one crystal system, in 2D space, there are four crystal systems, oblique, rectangular, square and hexagonal. The relation between three-dimensional crystal families, crystal systems and lattice systems is shown in the table, Note. To avoid confusion of terminology, the term trigonal lattice is not used, if the original structure and inverted structure are identical, then the structure is centrosymmetric. Still, even for non-centrosymmetric case, inverted structure in some cases can be rotated to align with the original structure and this is the case of non-centrosymmetric achiral structure. If the inverted structure cannot be rotated to align with the structure, then the structure is chiral
Crystal system
–
Hexagonal
hanksite crystal, with three-fold c-axis symmetry
Crystal system
–
The
diamond crystal structure belongs to the face-centered
cubic lattice, with a repeated 2-atom pattern.
5.
Dodecahedron
–
In geometry, a dodecahedron is any polyhedron with twelve flat faces. The most familiar dodecahedron is the dodecahedron, which is a Platonic solid. There are also three regular star dodecahedra, which are constructed as stellations of the convex form, all of these have icosahedral symmetry, order 120. The pyritohedron is a pentagonal dodecahedron, having the same topology as the regular one. The rhombic dodecahedron, seen as a case of the pyritohedron has octahedral symmetry. The elongated dodecahedron and trapezo-rhombic dodecahedron variations, along with the rhombic dodecahedra are space-filling, there are a large number of other dodecahedra. The convex regular dodecahedron is one of the five regular Platonic solids, the dual polyhedron is the regular icosahedron, having five equilateral triangles around each vertex. Like the regular dodecahedron, it has twelve pentagonal faces. However, the pentagons are not constrained to be regular, and its 30 edges are divided into two sets – containing 24 and 6 edges of the same length. The only axes of symmetry are three mutually perpendicular twofold axes and four threefold axes. Note that the regular dodecahedron can occur as a shape for quasicrystals with icosahedral symmetry. Its name comes from one of the two common crystal habits shown by pyrite, the one being the cube. The coordinates of the eight vertices of the cube are, The coordinates of the 12 vertices of the cross-edges are. When h =1, the six cross-edges degenerate to points, when h =0, the cross-edges are absorbed in the facets of the cube, and the pyritohedron reduces to a cube. When h = √5 − 1/2, the inverse of the golden ratio, a reflected pyritohedron is made by swapping the nonzero coordinates above. The two pyritohedra can be superimposed to give the compound of two dodecahedra as seen in the image here, the regular dodecahedron represents a special intermediate case where all edges and angles are equal. A tetartoid is a dodecahedron with chiral tetrahedral symmetry, like the regular dodecahedron, it has twelve identical pentagonal faces, with three meeting in each of the 20 vertices. However, the pentagons are not regular and the figure has no fivefold symmetry axes, although regular dodecahedra do not exist in crystals, the tetartoid form does
Dodecahedron
–
Cubic pyrite
Dodecahedron
–
Common dodecahedra
Dodecahedron
–
Pyritohedral
Dodecahedron
–
Ho-Mg-Zn
quasicrystal
6.
Blue
–
Blue is the colour between violet and green on the optical spectrum of visible light. Human eyes perceive blue when observing light with a wavelength between 450 and 495 nanometres, which is between 4500 and 4950 ångströms. Blues with a frequency and thus a shorter wavelength gradually look more violet, while those with a lower frequency. Pure blue, in the middle, has a wavelength of 470 nanometers, in painting and traditional colour theory, blue is one of the three primary colours of pigments, along with red and yellow, which can be mixed to form a wide gamut of colours. Red and blue mixed together form violet, blue and yellow together form green, Blue is also a primary colour in the RGB colour model, used to create all the colours on the screen of a television or computer monitor. The clear sky and the sea appear blue because of an optical effect known as Rayleigh scattering. When sunlight passes through the atmosphere, the wavelengths are scattered more widely by the oxygen and nitrogen molecules. An optical effect called Tyndall scattering, similar to Rayleigh scattering, explains blue eyes, distant objects appear more blue because of another optical effect called atmospheric perspective. Blue has been used for art and decoration since ancient times and it is the most important color in Judaism. In the Middle Ages, cobalt blue was used to colour the stained glass windows of cathedrals, beginning in the 9th century, Chinese artists used cobalt to make fine blue and white porcelain. Blue dyes for clothing were made from woad in Europe and indigo in Asia, in 1828 a synthetic ultramarine pigment was developed, and synthetic blue dyes and pigments gradually replaced mineral pigments and vegetable dyes. Pierre-Auguste Renoir, Vincent van Gogh and other late 19th century painters used ultramarine and cobalt blue not just to depict nature, in the late 18th century and 19th century, blue became a popular colour for military uniforms and police uniforms. In the 20th century, because blue was associated with harmony, it was chosen as the colour of the flags of the United Nations. Surveys in the US and Europe show that blue is the colour most commonly associated with harmony, faithfulness, confidence, distance, infinity, the imagination, cold, and sometimes with sadness. In US and European public opinion polls it is the most popular colour, Blue is the colour of light between violet and green on the visible spectrum. Blues also vary in shade or tint, darker shades of blue contain black or grey, darker shades of blue include ultramarine, cobalt blue, navy blue, and Prussian blue, while lighter tints include sky blue, azure, and Egyptian blue. Today most blue pigments and dyes are made by a chemical process, the modern English word blue comes from Middle English bleu or blewe, from the Old French bleu, a word of Germanic origin, related to the Old High German word blao. In heraldry, the azure is used for blue
Blue
–
Sky blue or pale
azure, mid-way on the RBG colour wheel between blue and cyan.
Blue
–
Blue
Blue
–
Extract of natural
indigo, the most popular blue dye before the invention of synthetic dyes. It was the colour of the first
blue jeans.
Blue
–
A block of
lapis lazuli, originally used to make ultramarine.
7.
Calcite
–
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate. The Mohs scale of hardness, based on scratch hardness comparison. Other polymorphs of calcium carbonate are the minerals aragonite and vaterite, aragonite will change to calcite at 380–470 °C, and vaterite is even less stable. Calcite is derived from the German Calcit, a term coined in the 19th century from the Latin word for lime and it is thus etymologically related to chalk. Calcite crystals are trigonal-rhombohedral, though actual calcite rhombohedra are rare as natural crystals, however, they show a remarkable variety of habits including acute to obtuse rhombohedra, tabular forms, prisms, or various scalenohedra. Calcite exhibits several twinning types adding to the variety of observed forms and it may occur as fibrous, granular, lamellar, or compact. Cleavage is usually in three directions parallel to the rhombohedron form and its fracture is conchoidal, but difficult to obtain. It has a defining Mohs hardness of 3, a gravity of 2.71. Color is white or none, though shades of gray, red, orange, yellow, green, blue, violet, brown, calcite is transparent to opaque and may occasionally show phosphorescence or fluorescence. A transparent variety called Iceland spar is used for optical purposes, acute scalenohedral crystals are sometimes referred to as dogtooth spar while the rhombohedral form is sometimes referred to as nailhead spar. Single calcite crystals display an optical property called birefringence and this strong birefringence causes objects viewed through a clear piece of calcite to appear doubled. The birefringent effect was first described by the Danish scientist Rasmus Bartholin in 1669, at a wavelength of ~590 nm calcite has ordinary and extraordinary refractive indices of 1.658 and 1.486, respectively. Between 190 and 1700 nm, the refractive index varies roughly between 1.9 and 1.5, while the extraordinary refractive index varies between 1.6 and 1.4. Calcite, like most carbonates, will dissolve with most forms of acid, calcite can be either dissolved by groundwater or precipitated by groundwater, depending on several factors including the water temperature, pH, and dissolved ion concentrations. Although calcite is fairly insoluble in water, acidity can cause dissolution of calcite. Ambient carbon dioxide, due to its acidity, has a slight solubilizing effect on calcite, calcite exhibits an unusual characteristic called retrograde solubility in which it becomes less soluble in water as the temperature increases. When conditions are right for precipitation, calcite forms mineral coatings that cement the existing rock grains together or it can fill fractures. On a landscape scale, continued dissolution of calcium carbonate-rich rocks can lead to the expansion and eventual collapse of cave systems, high-grade optical calcite was used in World War II for gun sights, specifically in bomb sights and anti-aircraft weaponry
Calcite
–
A one-inch calcite
rhomb that shows the
double image refraction property
Calcite
–
Crystal structure of calcite
Calcite
–
faceted calcite, oval cut, 1.12ct, Mexico.
Calcite
–
Doubly terminated calcite crystal.
8.
Pyrite
–
The mineral pyrite, or iron pyrite, also known as fools gold, is an iron sulfide with the chemical formula FeS2. This minerals metallic luster and pale brass-yellow hue give it a resemblance to gold. The color has led to the nicknames brass, brazzle. Pyrite is the most common of the sulfide minerals, the name pyrite is derived from the Greek πυρίτης, of fire or in fire, in turn from πύρ, fire. 1550, the term had become a term for all of the sulfide minerals. Pyrite is usually associated with other sulfides or oxides in quartz veins, sedimentary rock. Despite being nicknamed fools gold, pyrite is sometimes found in association with small quantities of gold, Gold and arsenic occur as a coupled substitution in the pyrite structure. In the Carlin–type gold deposits, arsenian pyrite contains up to 0.37 wt% gold, Pyrite has been used since classical times to manufacture copperas, that is, iron sulfate. Iron pyrite was heaped up and allowed to weather, the acidic runoff from the heap was then boiled with iron to produce iron sulfate. In the 15th century, such leaching began to replace the burning of sulfur as a source of sulfuric acid, by the 19th century, it had become the dominant method. Pyrite remains in use for the production of sulfur dioxide, for use in such applications as the paper industry. Thermal decomposition of pyrite into FeS and elemental sulfur starts at 540 °C, a newer commercial use for pyrite is as the cathode material in Energizer brand non-rechargeable lithium batteries. Pyrite is a material with a band gap of 0.95 eV. During the early years of the 20th century, pyrite was used as a detector in radio receivers. Pyrite detectors occupied a midway point between galena detectors and the more mechanically complicated perikon mineral pairs, Pyrite detectors can be as sensitive as a modern 1N34A germanium diode detector. Pyrite has been proposed as an abundant, inexpensive material in low-cost photovoltaic solar panels, synthetic iron sulfide was used with copper sulfide to create the photovoltaic material. Pyrite is used to make marcasite jewelry, marcasite jewelry, made from small faceted pieces of pyrite, often set in silver, was known since ancient times and was popular in the Victorian era. Marcasite jewelry does not actually contain the mineral marcasite, from the perspective of classical inorganic chemistry, which assigns formal oxidation states to each atom, pyrite is probably best described as Fe2+S22−
Pyrite
–
Pyrite cubic crystals on
marl from
Navajún,
La Rioja, Spain (size: 95 by 78 millimetres (3.7 by 3.1 in), 512 grams (18.1 oz); main crystal: 31 millimetres (1.2 in) on edge)
Pyrite
–
Pyrite from Ampliación a Victoria Mine,
Navajún,
La Rioja, Spain.
Pyrite
–
Dodecahedron - shaped crystals from Italy.
Pyrite
–
A pyrite cube (center) has dissolved away from a host rock, leaving behind trace gold.
9.
Crystal habit
–
In mineralogy, crystal habit is the characteristic external shape of an individual crystal or crystal group. A single crystals habit is a description of its shape and its crystallographic forms. Recognizing the habit may help in identifying a mineral, when the faces are well-developed due to uncrowded growth a crystal is called euhedral, one with partially developed faces is subhedral, and one with undeveloped crystal faces is called anhedral. The long axis of a quartz crystal typically has a six-sided prismatic habit with parallel opposite faces. Aggregates can be formed of individual crystals with euhedral to anhedral grains, the arrangement of crystals within the aggregate can be characteristic of certain minerals. For example, minerals used for asbestos insulation often grow in a fibrous habit, the terms used by mineralogists to report crystal habits describe the typical appearance of an ideal mineral. Recognizing the habit can aid in identification as some habits are characteristic, most minerals, however, do not display ideal habits due to conditions during crystallization. Minerals belonging to the crystal system do not necessarily exhibit the same habit. Some habits of a mineral are unique to its variety and locality, For example, while most sapphires form elongate barrel-shaped crystals, ordinarily, the latter habit is seen only in ruby. Sapphire and ruby are both varieties of the mineral, corundum. Some minerals may replace other existing minerals while preserving the originals habit, a classic example is tigers eye quartz, crocidolite asbestos replaced by silica. While quartz typically forms prismatic crystals, in tigers eye the original fibrous habit of crocidolite is preserved, the names of crystal habits are derived from, Predominant crystal faces. Abnormal grain growth Grain growth Crystallization
Crystal habit
–
Pyrite sun (or dollar) in laminated shale matrix. Between tightly spaced layers of shale, the aggregate was forced to grow in a laterally compressed, radiating manner. Under normal conditions, pyrite would form cubes or pyritohedrons.
Crystal habit
–
Goethite replacing
pyrite cubes
Crystal habit
–
Acicular
Crystal habit
–
Amygdaloidal
10.
Fracture (mineralogy)
–
In the field of mineralogy, fracture is the texture and shape of a rocks surface formed when a mineral is fractured. Minerals often have a highly distinctive fracture, making it a feature used in their identification. Fracture differs from cleavage in that the latter involves clean splitting along the planes of the minerals crystal structure. All minerals exhibit fracture, but when very strong cleavage is present, conchoidal fracture breakage that resembles the concentric ripples of a mussel shell. It often occurs in amorphous or fine-grained minerals such as flint, opal or obsidian, subconchoidal fracture is similar to conchoidal fracture, but with less significant curvature. Earthy fracture is reminiscent of freshly broken soil and it is frequently seen in relatively soft, loosely bound minerals, such as limonite, kaolinite and aluminite. Hackly fracture is jagged, sharp and not even and it occurs when metals are torn, and so is often encountered in native metals such as copper and silver. Splintery fracture comprises sharp elongated points and it is particularly seen in fibrous minerals such as chrysotile, but may also occur in non-fibrous minerals such as kyanite. Uneven fracture is a surface or one with random irregularities. It occurs in a range of minerals including arsenopyrite, pyrite and magnetite. Rudolf Duda and Lubos Rejl, Minerals of the World http, //www. galleries. com/minerals/property/fracture. htm
Fracture (mineralogy)
–
Obsidian
Fracture (mineralogy)
–
Limonite
Fracture (mineralogy)
–
Native copper
Fracture (mineralogy)
–
Chrysotile
11.
Mohs scale of mineral hardness
–
The Mohs scale of mineral hardness is a qualitative ordinal scale characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. Created in 1812 by German geologist and mineralogist Friedrich Mohs, it is one of several definitions of hardness in materials science, while greatly facilitating the identification of minerals in the field, the Mohs scale does not show how well hard materials perform in an industrial setting. Despite its lack of precision, the Mohs scale is highly relevant for field geologists, the Mohs scale hardness of minerals can be commonly found in reference sheets. Reference materials may be expected to have a uniform Mohs hardness, the Mohs scale of mineral hardness is based on the ability of one natural sample of mineral to scratch another mineral visibly. The samples of matter used by Mohs are all different minerals, Minerals are pure substances found in nature. Rocks are made up of one or more minerals, as the hardest known naturally occurring substance when the scale was designed, diamonds are at the top of the scale. The hardness of a material is measured against the scale by finding the hardest material that the material can scratch. For example, if material is scratched by apatite but not by fluorite. Scratching a material for the purposes of the Mohs scale means creating non-elastic dislocations visible to the naked eye, frequently, materials that are lower on the Mohs scale can create microscopic, non-elastic dislocations on materials that have a higher Mohs number. The Mohs scale is an ordinal scale. For example, corundum is twice as hard as topaz, the table below shows the comparison with the absolute hardness measured by a sclerometer, with pictorial examples. On the Mohs scale, a streak plate has a hardness of 7.0, using these ordinary materials of known hardness can be a simple way to approximate the position of a mineral on the scale. The table below incorporates additional substances that may fall between levels, Comparison between Hardness and Hardness, Mohs hardness of elements is taken from G. V, samsonov in Handbook of the physicochemical properties of the elements, IFI-Plenum, New York, USA,1968. The Hardness of Minerals and Rocks
Mohs scale of mineral hardness
Mohs scale of mineral hardness
Mohs scale of mineral hardness
Mohs scale of mineral hardness
12.
Lustre (mineralogy)
–
Lustre or luster is the way light interacts with the surface of a crystal, rock, or mineral. The word traces its origins back to the latin lux, meaning light, a range of terms are used to describe lustre, such as earthy, metallic, greasy, and silky. Similarly, the term refers to a glassy lustre. A list of terms is given below. Lustre varies over a continuum, and so there are no rigid boundaries between the different types of lustre. The terms are frequently combined to describe types of lustre. Some minerals exhibit unusual optical phenomena, such as asterism or chatoyancy, a list of such phenomena is given below. Adamantine minerals possess a superlative lustre, which is most notably seen in diamond, such minerals are transparent or translucent, and have a high refractive index. Minerals with an adamantine lustre are uncommon, with examples being cerussite. Minerals with a degree of lustre are referred to as subadamantine, with some examples being garnet. Dull minerals exhibit little to no lustre, due to coarse granulations which scatter light in all directions, a distinction is sometimes drawn between dull minerals and earthy minerals, with the latter being coarser, and having even less lustre. Greasy minerals resemble fat or grease, a greasy lustre often occurs in minerals containing a great abundance of microscopic inclusions, with examples including opal and cordierite. Many minerals with a greasy lustre also feel greasy to the touch, metallic minerals have the lustre of polished metal, and with ideal surfaces will work as a reflective surface. Examples include galena, pyrite and magnetite, pearly minerals consist of thin transparent co-planar sheets. Light reflecting from these layers give them a lustre reminiscent of pearls, such minerals possess perfect cleavage, with examples including muscovite and stilbite. Resinous minerals have the appearance of resin, chewing gum or plastic, a principal example is amber, which is a form of fossilized resin. Silky minerals have an arrangement of extremely fine fibres, giving them a lustre reminiscent of silk. Examples include asbestos, ulexite and the satin spar variety of gypsum, a fibrous lustre is similar, but has a coarser texture
Lustre (mineralogy)
–
Cut diamonds.
Lustre (mineralogy)
–
Kaolinite
Lustre (mineralogy)
–
Moss
opal
Lustre (mineralogy)
–
Pyrite
13.
Streak (mineralogy)
–
The streak of a mineral is the color of the powder produced when it is dragged across an un-weathered surface. If no streak seems to be made, the streak is said to be white or colorless. Streak is particularly important as a diagnostic for opaque and colored materials and it is less useful for silicate minerals, most of which have a white streak or are too hard to powder easily. The apparent color of a mineral can vary widely because of impurities or a disturbed macroscopic crystal structure. Small amounts of an impurity that strongly absorbs a particular wavelength can radically change the wavelengths of light that are reflected by the specimen, and thus change the apparent color. However, when the specimen is dragged to produce a streak, it is broken into randomly oriented microscopic crystals, the surface across which the mineral is dragged is called a streak plate, and is generally made of unglazed porcelain tile. In the absence of a plate, the unglazed underside of a porcelain bowl or vase or the back of a glazed tile will work. Sometimes a streak is more easily or accurately described by comparing it with the streak made by another streak plate. Because the trail left behind results from the mineral being crushed into powder, in case of harder minerals, the color of the powder can be determined by filing or crushing with a hammer a small sample, which is then usually rubbed on a streak plate. Most minerals that are harder have a white streak. Some minerals leave a similar to their natural color, such as cinnabar. Other minerals leave surprising colors, such as fluorite, which always has a streak, although it can appear in purple, blue, yellow. Hematite, which is black in appearance, leaves a red streak which accounts for its name, galena, which can be similar in appearance to hematite, is easily distinguished by its gray streak. Hamilton, W. R. Cambridge Guide to Minerals, Rocks, the Encyclopedia of Gemstones and Minerals. New York, Facts on File. p.251, physical Characteristics of Minerals, at Introduction to Mineralogy by Andrea Bangert What is Streak
Streak (mineralogy)
–
Streak plates with
pyrite (left) and
rhodochrosite (right)
14.
Specific gravity
–
This page is about the measurement using water as a reference. For a general use of gravity, see relative density. See intensive property for the property implied by specific, Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance. The reference substance is always water at its densest for liquids. Nonetheless, the temperature and pressure must be specified for both the sample and the reference, pressure is nearly always 1 atm. Temperatures for both sample and reference vary from industry to industry, in British beer brewing, the practice for specific gravity as specified above is to multiply it by 1000. Being a ratio of densities, specific gravity is a dimensionless quantity, Specific gravity varies with temperature and pressure, reference and sample must be compared at the same temperature and pressure or be corrected to a standard reference temperature and pressure. Substances with a gravity of 1 are neutrally buoyant in water. Those with SG greater than 1 are denser than water and will, disregarding surface tension effects and those with an SG less than 1 are less dense than water and will float on it. In scientific work, the relationship of mass to volume is expressed directly in terms of the density of the substance under study. It is in industry where specific gravity finds wide application, often for historical reasons. True specific gravity can be expressed mathematically as, S G true = ρ sample ρ H2 O where ρ sample is the density of the sample, the density of water varies with temperature and pressure as does the density of the sample. So it is necessary to specify the temperatures and pressures at which the densities or weights were determined and it is nearly always the case that measurements are made at 1 nominal atmosphere. For true specific gravity calculations, air pressure must be considered, temperatures are specified by the notation with T s representing the temperature at which the samples density was determined and T r the temperature at which the reference density is specified. For example, SG would be understood to mean that the density of the sample was determined at 20°C and of the water at 4°C. Taking into account different sample and reference temperatures, we note that, while S G H2 O =1.000000, it is also the case that S G H2 O =0.998203 /0.999840 =0.998363. Here, temperature is being specified using the current ITS-90 scale, on the previous IPTS-68 scale, the densities at 20 °C and 4 °C are 0.9982071 and 0.9999720 respectively, resulting in an SG value for water of 0.9982343. For example, in the industry, the Plato table lists sucrose concentration by weight against true SG
Specific gravity
–
Testing specific gravity of fuel.
15.
Refractive index
–
In optics, the refractive index or index of refraction n of a material is a dimensionless number that describes how light propagates through that medium. It is defined as n = c v, where c is the speed of light in vacuum, for example, the refractive index of water is 1.333, meaning that light travels 1.333 times faster in a vacuum than it does in water. The refractive index determines how light is bent, or refracted. The refractive indices also determine the amount of light that is reflected when reaching the interface, as well as the angle for total internal reflection. This implies that vacuum has a index of 1. The refractive index varies with the wavelength of light and this is called dispersion and causes the splitting of white light into its constituent colors in prisms and rainbows, and chromatic aberration in lenses. Light propagation in absorbing materials can be described using a refractive index. The imaginary part then handles the attenuation, while the real part accounts for refraction, the concept of refractive index is widely used within the full electromagnetic spectrum, from X-rays to radio waves. It can also be used with wave phenomena such as sound, in this case the speed of sound is used instead of that of light and a reference medium other than vacuum must be chosen. Thomas Young was presumably the person who first used, and invented, at the same time he changed this value of refractive power into a single number, instead of the traditional ratio of two numbers. The ratio had the disadvantage of different appearances, newton, who called it the proportion of the sines of incidence and refraction, wrote it as a ratio of two numbers, like 529 to 396. Hauksbee, who called it the ratio of refraction, wrote it as a ratio with a fixed numerator, hutton wrote it as a ratio with a fixed denominator, like 1.3358 to 1. Young did not use a symbol for the index of refraction, in the next years, others started using different symbols, n, m, and µ. For visible light most transparent media have refractive indices between 1 and 2, a few examples are given in the adjacent table. These values are measured at the yellow doublet D-line of sodium, with a wavelength of 589 nanometers, gases at atmospheric pressure have refractive indices close to 1 because of their low density. Almost all solids and liquids have refractive indices above 1.3, aerogel is a very low density solid that can be produced with refractive index in the range from 1.002 to 1.265. Moissanite lies at the end of the range with a refractive index as high as 2.65. Most plastics have refractive indices in the range from 1.3 to 1.7, for infrared light refractive indices can be considerably higher
Refractive index
–
Thomas Young coined the term index of refraction.
Refractive index
–
A
ray of light being
refracted in a plastic block.
Refractive index
–
Diamonds have a very high refractive index of 2.42.
Refractive index
–
A
split-ring resonator array arranged to produce a negative index of refraction for
microwaves.
16.
Gemstone
–
A gemstone is a piece of mineral crystal which, in cut and polished form, is used to make jewelry or other adornments. However, certain rocks or organic materials that are not minerals are used for jewelry and are therefore often considered to be gemstones as well. Most gemstones are hard, but some soft minerals are used in jewelry because of their luster or other properties that have aesthetic value. Rarity is another characteristic that lends value to a gemstone, apart from jewelry, from earliest antiquity engraved gems and hardstone carvings, such as cups, were major luxury art forms. A gem maker is called a lapidary or gemcutter, a worker is a diamantaire. The carvings of Carl Fabergé are significant works in this tradition, the traditional classification in the West, which goes back to the ancient Greeks, begins with a distinction between precious and semi-precious, similar distinctions are made in other cultures. In modern usage the precious stones are diamond, ruby, sapphire, other stones are classified by their color, translucency and hardness. Another unscientific term for semi-precious gemstones used in art history and archaeology is hardstone, in modern times gemstones are identified by gemologists, who describe gems and their characteristics using technical terminology specific to the field of gemology. The first characteristic a gemologist uses to identify a gemstone is its chemical composition, for example, diamonds are made of carbon and rubies of aluminium oxide. Next, many gems are crystals which are classified by their crystal system such as cubic or trigonal or monoclinic, another term used is habit, the form the gem is usually found in. For example, diamonds, which have a crystal system, are often found as octahedrons. Gemstones are classified into different groups, species, and varieties, for example, ruby is the red variety of the species corundum, while any other color of corundum is considered sapphire. Other examples are the Emerald, aquamarine, red beryl, goshenite, heliodor, and morganite, gems are characterized in terms of refractive index, dispersion, specific gravity, hardness, cleavage, fracture, and luster. They may exhibit pleochroism or double refraction and they may have luminescence and a distinctive absorption spectrum. Material or flaws within a stone may be present as inclusions, gemstones may also be classified in terms of their water. This is a grading of the gems luster, transparency. Very transparent gems are considered first water, while second or third water gems are those of a lesser transparency, there is no universally accepted grading system for gemstones. Diamonds are graded using a system developed by the Gemological Institute of America in the early 1950s, historically, all gemstones were graded using the naked eye
Gemstone
–
A selection of gemstone pebbles made by tumbling rough rock with abrasive grit, in a rotating drum. The biggest pebble here is 40 mm long (1.6 inches).
Gemstone
–
Group of precious and semiprecious stones —both uncut and faceted— including (clockwise from top left)
diamond, uncut synthetic
sapphire,
ruby, uncut
emerald, and
amethyst crystal cluster.
Gemstone
–
Spanish emerald and gold pendant at
Victoria and Albert Museum
Gemstone
–
Enamelled gold, amethyst and pearl pendant, about 1880, Pasquale Novissimo (1844–1914), V&A Museum number M.36-1928
17.
Ancient history
–
Ancient history is the aggregate of past events from the beginning of recorded human history and extending as far as the Early Middle Ages or the Postclassical Era. The span of recorded history is roughly 5,000 years, beginning with Sumerian Cuneiform script, the term classical antiquity is often used to refer to history in the Old World from the beginning of recorded Greek history in 776 BC. This roughly coincides with the date of the founding of Rome in 753 BC, the beginning of the history of ancient Rome. In India, ancient history includes the period of the Middle Kingdoms, and, in China. Historians have two major avenues which they take to better understand the ancient world, archaeology and the study of source texts, primary sources are those sources closest to the origin of the information or idea under study. Primary sources have been distinguished from secondary sources, which cite, comment on. Archaeology is the excavation and study of artefacts in an effort to interpret, archaeologists excavate the ruins of ancient cities looking for clues as to how the people of the time period lived. The study of the ancient cities of Harappa, Mohenjo-daro, the city of Pompeii, an ancient Roman city preserved by the eruption of a volcano in AD79. Its state of preservation is so great that it is a window into Roman culture and provided insight into the cultures of the Etruscans. The Terracotta Army, the mausoleum of the First Qin Emperor in ancient China, the discovery of Knossos by Minos Kalokairinos and Sir Arthur Evans. The discovery of Troy by Heinrich Schliemann, most of what is known of the ancient world comes from the accounts of antiquitys own historians. Although it is important to take account the bias of each ancient author. Some of the more notable ancient writers include Herodotus, Thucydides, Arrian, Plutarch, Polybius, Sima Qian, Sallust, Livy, Josephus, Suetonius, furthermore, the reliability of the information obtained from these surviving records must be considered. Few people were capable of writing histories, as literacy was not widespread in almost any culture until long after the end of ancient history, the earliest known systematic historical thought emerged in ancient Greece, beginning with Herodotus of Halicarnassus. He was also the first to distinguish between cause and immediate origins of an event, the Roman Empire was one of the ancient worlds most literate cultures, but many works by its most widely read historians are lost. Indeed, only a minority of the work of any major Roman historian has survived, prehistory is the period before written history. The early human migrations in the Lower Paleolithic saw Homo erectus spread across Eurasia 1.8 million years ago, the controlled use of fire occurred 800,000 years ago in the Middle Paleolithic. 250,000 years ago, Homo sapiens emerged in Africa, 60–70,000 years ago, Homo sapiens migrated out of Africa along a coastal route to South and Southeast Asia and reached Australia
Ancient history
–
Khafre's Pyramid (
4th dynasty) and
Great Sphinx of Giza (c. 2500 BC or perhaps earlier)
Ancient history
–
The Mediterranean in c. the 4th century BC. Phoenician cities are labelled in yellow, Greek cities in red, and other cities in grey.
Ancient history
–
Eastern Hemisphere in 500 BC.
18.
Sar-i Sang
–
Sar-i Sang is a settlement in the Kuran Wa Munjan District of Badakhshan Province, Afghanistan, famous for its ancient lapis lazuli mines producing the worlds finest lapis. Sar-i Sang lapis lazuli mine probably dates from proto-historic times and it consists of one old disused shaft and two new shafts. This was the source of lapis lazuli in the ancient world, with lapis from here occurring in such famous archaeological discoveries as the Royal Treasure of Ur. Lapis lazuli Mount Imeon Warwick Ball,2008, The Monuments of Afghanistan, History, Archaeology and Architecture,261, Warwick Ball,1982, Archaeological Gazetteer of Afghanistan, Volume I,1001
Sar-i Sang
–
Lazurite from Sar-e Sang
Sar-i Sang
–
Another Sar-e Sang Lazurite crystal, with the classic deep azure-blue color. Crystal is 4.5 cm wide.
19.
Shortugai
–
Shortugai was an Indus civilization trading colony established around 2000 BC on the Oxus river near the lapis mines in northern Afghanistan. According to Sergent, not one of the characteristics of the Harappan cultural complex is missing from it. The town consists of two hills called A and B by the excavators, one of them was once the town proper, the other one the citadel. Each of them is about 2 hectares large, typical finds of the Indus Valley Civilization include one seal with a short inscription, clay models of cattle with carts and painted pottery. Pottery with Harappan design, jars, beakers, bronze objects, gold pieces, lapis lazuli beads, other types of beads, drill heads, square seals with animal motiff and script confirms this as a site belonging to Indus Valley Civilisation. A ploughed field with flax seeds in this site indicate dry land farming, shortugai was a trading post of Harappan times and it seems to be connected with lapis lazuli mines located in the surrounding area. It also might have connections with tin trade and camel trade, henri-Paul Francfort, Fouilles de Shortughai, Recherches sur LAsie Centrale Protohistorique Paris, Diffusion de Boccard,1989
Shortugai
–
Part of the excavations
20.
Badakhshan
–
Badakhshan is a historic region comprising parts of what is now northeastern Afghanistan and southeastern Tajikistan. The name is retained in Badakhshan Province, which is one of the 34 provinces of Afghanistan and is located in North-East Afghanistan, much of historic Badakhshan lies within Tajikistans Gorno-Badakhshan Autonomous Region located in the south-eastern part of the country. The music of Badakhshan is an important part of the cultural heritage. Badakhshan has a diverse ethno-linguistic and religious community, tajiks and Pamiris are the majority while a tiny minority of Kyrgyzs and Uzbeks also are found in their own villages. There are also groups of speakers of several Pamir languages of the Eastern Iranian language group, during the 20th century within Gorno-Badakhshan Autonomous Region in Tajikistan the speakers of Pamir languages formed their own separate ethnic identity as Pamiris. The Pamiri people were not officially recognized as an ethnic group in Tajikistan. The main religions of Badakhshan are Ismaili Islam and Sunni Islam, the people of this province have a rich cultural heritage and they have preserved unique ancient forms of music, poetry and dance. Badakhshan was an important trading center during antiquity, lapis lazuli was traded exclusively from there as early as the second half of the 4th millennium BC. Badakhshan was an important region when the Silk Road passed through and its significance is its geo-economic role in trades of silk and ancient commodities transactions between the East and West. According to Marco Polo, Badashan/ Badakshan was a province where Balas ruby could be found under the mountain Syghinan, the region was ruled over by the mirs of Badakhshan. Sultan Muhammad of Badakhshan was the last of a series of kings who traced their descent to Alexander the Great, when Mahmud died, Amir Khusroe Khan, one of his nobles, blinded Baysinghar Mirza, killed the second prince, and ruled as usurper. He submitted to Mughal Emperor Babur in 1504 CE, when Babur took Kandahar in 1506 CE, from Shah Beg Arghun, he sent Khan Mirza as governor to Badakhshan. A son was born to Khan Mirza by the name of Mirza Sulaiman in 1514 CE and they were released by Emperor Humayun in 1545, and took again possession of Badakhshan. Bent on making conquests, he invaded Balkh in 1560, but had to return and his son, Mirza Ibrahim, was killed in battle. When Akbar became Mughal Emperor, his stepbrother Mirza Muhammad Hakims mother had killed by Shah Abul Maali. He returned to Kabul in 1566, when Akbars troops had left that country, Mirza Sulaimans wife was Khurram Begum, of the Kipchak tribe. She was clever and had her husband so much in her power and her enemy was Muhtarim Khanum, the widow of Prince Kamran Mirza. Mirza Sulaiman wanted to marry her, but Khurram Begum got her married, against her will, to Mirza Ibrahim, by whom she had a son, Mirza Shahrukh
Badakhshan
–
Sultan Muḥammad Vays offers Babur a healthy horse to replace his ailing one
Badakhshan
–
Map of Badakhshan, divided between
Tajikistan -
Gorno-Badakhshan Autonomous Province, in the north and
Afghanistan -
Badakhshan Province in the south
Badakhshan
–
In 1756 Badakhshan emir made the Chinese
Qing dynasty to recognize the Elder of Badakhshan (the "grey beard") at Alti as sovereign in
Kashgar and levied taxes on the city and parts of the province of
Xinjiang
Badakhshan
–
Friendship Bridge between
Tajikistan, and
Afghanistan, over the
Panj river in
Khwahan and
Shuro-obod.
21.
Afghanistan
–
Afghanistan, officially the Islamic Republic of Afghanistan, is a landlocked country located within South Asia and Central Asia. It has a population of approximately 32 million, making it the 42nd most populous country in the world. It is bordered by Pakistan in the south and east, Iran in the west, Turkmenistan, Uzbekistan, and Tajikistan in the north and its territory covers 652,000 km2, making it the 41st largest country in the world. The land also served as the source from which the Kushans, Hephthalites, Samanids, Saffarids, Ghaznavids, Ghorids, Khiljis, Mughals, Hotaks, Durranis, the political history of the modern state of Afghanistan began with the Hotak and Durrani dynasties in the 18th century. In the late 19th century, Afghanistan became a state in the Great Game between British India and the Russian Empire. Following the Third Anglo-Afghan War in 1919, King Amanullah unsuccessfully attempted to modernize the country and it remained peaceful during Zahir Shahs forty years of monarchy. A series of coups in the 1970s was followed by a series of wars that devastated much of Afghanistan. The name Afghānistān is believed to be as old as the ethnonym Afghan, the root name Afghan was used historically in reference to a member of the ethnic Pashtuns, and the suffix -stan means place of in Persian. Therefore, Afghanistan translates to land of the Afghans or, more specifically in a historical sense, however, the modern Constitution of Afghanistan states that he word Afghan shall apply to every citizen of Afghanistan. An important site of historical activities, many believe that Afghanistan compares to Egypt in terms of the historical value of its archaeological sites. The country sits at a unique nexus point where numerous civilizations have interacted and it has been home to various peoples through the ages, among them the ancient Iranian peoples who established the dominant role of Indo-Iranian languages in the region. At multiple points, the land has been incorporated within large regional empires, among them the Achaemenid Empire, the Macedonian Empire, the Indian Maurya Empire, and the Islamic Empire. Archaeological exploration done in the 20th century suggests that the area of Afghanistan has been closely connected by culture and trade with its neighbors to the east, west. Artifacts typical of the Paleolithic, Mesolithic, Neolithic, Bronze, urban civilization is believed to have begun as early as 3000 BCE, and the early city of Mundigak may have been a colony of the nearby Indus Valley Civilization. More recent findings established that the Indus Valley Civilisation stretched up towards modern-day Afghanistan, making the ancient civilisation today part of Pakistan, Afghanistan, in more detail, it extended from what today is northwest Pakistan to northwest India and northeast Afghanistan. An Indus Valley site has found on the Oxus River at Shortugai in northern Afghanistan. There are several smaller IVC colonies to be found in Afghanistan as well, after 2000 BCE, successive waves of semi-nomadic people from Central Asia began moving south into Afghanistan, among them were many Indo-European-speaking Indo-Iranians. These tribes later migrated further into South Asia, Western Asia, the region at the time was referred to as Ariana
Afghanistan
–
History of Afghanistan
Afghanistan
–
Flag
Afghanistan
–
Bilingual (
Greek and
Aramaic)
edict by Emperor
Ashoka from the 3rd century BCE discovered in the southern city of
Kandahar
Afghanistan
–
One of the
Buddhas of Bamiyan.
Buddhism was widespread in the region before the
Islamic conquest of Afghanistan.
22.
Indus Valley Civilisation
–
The Indus Valley Civilisation was a Bronze Age civilisation mainly in the northwestern regions of South Asia, extending from what today is northeast Afghanistan to Pakistan and northwest India. Along with ancient Egypt and Mesopotamia it was one of three early civilisations of the Old World, and of the three, the most widespread, at its peak, the Indus Civilisation may have had a population of over five million. Inhabitants of the ancient Indus river valley developed new techniques in handicraft, the Indus cities are noted for their urban planning, baked brick houses, elaborate drainage systems, water supply systems, and clusters of large non-residential buildings. The discovery of Harappa, and soon afterwards, Mohenjo-Daro, was the culmination of work beginning in 1861 with the founding of the Archaeological Survey of India in the British Raj, excavation of Harappan sites has been ongoing since 1920, with important breakthroughs occurring as recently as 1999. This Harappan civilisation is called the Mature Harappan culture to distinguish it from the cultures immediately preceding and following it. The early Harappan cultures were preceded by local Neolithic agricultural villages, as of 1999, over 1,056 cities and settlements had been found, of which 96 have been excavated, mainly in the general region of the Indus and Ghaggar-Hakra Rivers and their tributaries. Among the settlements were the urban centres of Harappa, Mohenjo-daro, Dholavira, Ganeriwala in Cholistan. The Harappan language is not directly attested and its affiliation is uncertain since the Indus script is still undeciphered, a relationship with the Dravidian or Elamo-Dravidian language family is favoured by a section of scholars. Recently, Indus sites have been discovered in Pakistans northwestern Frontier Province as well, other IVC colonies can be found in Afghanistan while smaller isolated colonies can be found as far away as Turkmenistan and in Maharashtra. The largest number of colonies are in the Punjab, Sindh, Rajasthan, Haryana, Indus Valley sites have been found most often on rivers, but also on the ancient seacoast, for example, Balakot, and on islands, for example, Dholavira. There is evidence of dry river beds overlapping with the Hakra channel in Pakistan, many Indus Valley sites have been discovered along the Ghaggar-Hakra beds. Among them are, Rupar, Rakhigarhi, Sothi, Kalibangan, Harappan Civilisation remains the correct one, according to the common archaeological usage of naming a civilisation after its first findspot. John wrote, I was much exercised in my mind how we were to get ballast for the line of the railway and they were told of an ancient ruined city near the lines, called Brahminabad. Visiting the city, he found it full of hard well-burnt bricks, and, convinced there was a grand quarry for the ballast I wanted. These bricks now provided ballast along 93 miles of the track running from Karachi to Lahore. In 1872–75, Alexander Cunningham published the first Harappan seal and it was half a century later, in 1912, that more Harappan seals were discovered by J. J. H. MacKay, and Marshall. By 1931, much of Mohenjo-Daro had been excavated, but excavations continued, such as that led by Sir Mortimer Wheeler, director of the Archaeological Survey of India in 1944. Among other archaeologists who worked on IVC sites before the independence in 1947 were Ahmad Hasan Dani, Brij Basi Lal, Nani Gopal Majumdar, and Sir Marc Aurel Stein
Indus Valley Civilisation
–
Indus Valley Civilization
Indus Valley Civilisation
–
Ceremonial vessel, Harappan, 2600–2450 BCE.
LACMA
Indus Valley Civilisation
–
Excavated ruins of
Mohenjo-daro, with the
Great Bath in the front
Indus Valley Civilisation
–
Indus Valley pottery, 2500–1900 BCE
23.
Neolithic
–
It ended when metal tools became widespread. The Neolithic is a progression of behavioral and cultural characteristics and changes, including the use of wild and domestic crops, the beginning of the Neolithic culture is considered to be in the Levant about 10, 200–8800 BC. It developed directly from the Epipaleolithic Natufian culture in the region, whose people pioneered the use of wild cereals, which then evolved into true farming. The Natufian period was between 12,000 and 10,200 BC, and the so-called proto-Neolithic is now included in the Pre-Pottery Neolithic between 10,200 and 8800 BC. By 10, 200–8800 BC, farming communities arose in the Levant and spread to Asia Minor, North Africa, Mesopotamia is the site of the earliest developments of the Neolithic Revolution from around 10,000 BC. Early Neolithic farming was limited to a range of plants, both wild and domesticated, which included einkorn wheat, millet and spelt, and the keeping of dogs, sheep. By about 6900–6400 BC, it included domesticated cattle and pigs, the establishment of permanently or seasonally inhabited settlements, not all of these cultural elements characteristic of the Neolithic appeared everywhere in the same order, the earliest farming societies in the Near East did not use pottery. Early Japanese societies and other East Asian cultures used pottery before developing agriculture, unlike the Paleolithic, when more than one human species existed, only one human species reached the Neolithic. The term Neolithic derives from the Greek νέος néos, new and λίθος líthos, stone, the term was invented by Sir John Lubbock in 1865 as a refinement of the three-age system. In the Middle East, cultures identified as Neolithic began appearing in the 10th millennium BC, early development occurred in the Levant and from there spread eastwards and westwards. Neolithic cultures are attested in southeastern Anatolia and northern Mesopotamia by around 8000 BC. The total excavated area is more than 1,200 square yards, the Neolithic 1 period began roughly 10,000 years ago in the Levant. A temple area in southeastern Turkey at Göbekli Tepe dated around 9500 BC may be regarded as the beginning of the period. This site was developed by nomadic tribes, evidenced by the lack of permanent housing in the vicinity. At least seven stone circles, covering 25 acres, contain limestone pillars carved with animals, insects, Stone tools were used by perhaps as many as hundreds of people to create the pillars, which might have supported roofs. Other early PPNA sites dating to around 9500–9000 BC have been found in Jericho, Israel, Gilgal in the Jordan Valley, the start of Neolithic 1 overlaps the Tahunian and Heavy Neolithic periods to some degree. The major advance of Neolithic 1 was true farming, in the proto-Neolithic Natufian cultures, wild cereals were harvested, and perhaps early seed selection and re-seeding occurred. The grain was ground into flour, emmer wheat was domesticated, and animals were herded and domesticated
Neolithic
–
An array of Neolithic artifacts, including bracelets, axe heads, chisels, and polishing tools. Neolithic stone artifacts are by definition polished and, except for specialty items, not chipped.
Neolithic
–
Algerian cave paintings depicting hunting scenes
Neolithic
–
Female figure from
Tumba Madžari,
Republic of Macedonia
Neolithic
–
Skara Brae, Scotland. Evidence of home furnishings (shelves)
24.
Mehrgarh
–
Mehrgarh, sometimes anglicized as Mehergarh or Mehrgar, is a Neolithic site located near the Bolan Pass on the Kacchi Plain of Balochistan, Pakistan, to the west of the Indus River valley. The earliest settlement at Mehrgarh, in the northeast corner of the 495-acre site, was a farming village which was inhabited from circa 6500 BCE. It is one of the earliest sites with evidence of farming and herding in South Asia, archaeological material has been found in six mounds, and about 32,000 artifacts have been collected. Mehrgarh is now seen as a precursor to the Indus Valley Civilization, displaying the whole sequence from earliest settlement, jean-Francois Jarrige argues for an independent origin of Mehrgarh. But given the originality of Mehrgarh, Jarrige concludes that Mehrgarh has a local background. Gallego Romero notes that Indians who are lactose-tolerant show a genetic pattern regarding this tolerance which is characteristic of the common European mutation. According to Romero, this suggests that the most common lactose tolerance mutation made a migration out of the Middle East less than 10,000 years ago. They further note that he earliest evidence of cattle herding in south Asia comes from the Indus River Valley site of Mehrgarh and is dated to 7,000 YBP, Archaeologists divide the occupation at the site into eight periods. The Mehrgarh Period I was Neolithic and aceramic, without the use of pottery, the earliest farming in the area was developed by semi-nomadic people using plants such as wheat and barley and animals such as sheep, goats and cattle. The settlement was established with simple mud buildings and most of them had four internal subdivisions, ornaments of sea shell, limestone, turquoise, lapis lazuli and sandstone have been found, along with simple figurines of women and animals. Sea shells from far sea shore and lapis lazuli found as far away as present-day Badakshan, Afghanistan shows good contact with those areas, a single ground stone axe was discovered in a burial, and several more were obtained from the surface. These ground stone axes are the earliest to come from a context in the South Asia. Periods I, II and III are contemporaneous with another site called Kili Gul Mohammed, in April 2006, it was announced in the scientific journal Nature that the oldest evidence for the drilling of human teeth in vivo was found in Mehrgarh. According to the authors, their discoveries point to a tradition of proto-dentistry in the farming cultures of that region. Here we describe eleven drilled molar crowns from nine adults discovered in a Neolithic graveyard in Pakistan that dates from 7,500 to 9,000 years ago and these findings provide evidence for a long tradition of a type of proto-dentistry in an early farming culture. The Mehrgarh Period II and Merhgarh Period III were ceramic Neolithic, using pottery, Period II is at site MR4 and Period III is at MR2. Much evidence of manufacturing activity has been found and more advanced techniques were used, glazed faience beads were produced and terracotta figurines became more detailed. Figurines of females were decorated with paint and had diverse hairstyles, two flexed burials were found in Period II with a red ochre cover on the body
Mehrgarh
–
Map of Pakistan showing Mehrgarh in relation to the cities of Quetta, Kalat, and Sibi and the Kachi Plain of Balochistan.
Mehrgarh
Mehrgarh
–
A figurine from Mehrgarh, similar to the
Venus figurines
25.
Caucasus
–
The Caucasus /ˈkɔːkəsəs/ or Caucasia /kɔːˈkeɪʒə/ is a region at the border of Europe and Asia, situated between the Black and the Caspian seas. It is home to the Caucasus Mountains, which contain Europes highest mountain, politically, the Caucasus region is separated between northern and southern parts. The southern parts consist of independent sovereign states, and the parts are under the jurisdiction of the Russian Federation. The region is known for its diversity, aside from Indo-European and Turkic languages, the Kartvelian, Northwest Caucasian. Pliny the Elders Natural History derives the name of the Caucasus from Scythian kroy-khasis, German linguist Paul Kretschmer notes that the Latvian word Kruvesis also means ice. According to German philologists Otto Schrader and Alfons A. Nehring, the South Caucasus region and southern Dagestan were the furthest points of Persian expansions, with areas to the north of Caucasus Mountains practically impregnable. The mythological mountain of Qaf, the worlds highest mountain that ancient lore shrouded in mystery, was said to be situated in this region, therefore, the Caucasus might be associated with the legendary mountain. The Ciscaucasus contains the majority of the Greater Caucasus Mountain range. It includes Southwestern Russia and northern parts of Georgia and Azerbaijan, the Transcaucasus is bordered on the north by Russia, on the west by the Black Sea and Turkey, on the east by the Caspian Sea, and on the south by Iran. It includes the Caucasus Mountains and surrounding lowlands, all of Armenia, Azerbaijan and Georgia are in South Caucasus. The main Greater Caucasus range is generally perceived to be the line between Asia and Europe. The highest peak in the Caucasus is Mount Elbrus in the western Ciscaucasus in Russia, the Caucasus is one of the most linguistically and culturally diverse regions on Earth. The nation states that comprise the Caucasus today are the post-Soviet states Georgia, Armenia, three territories in the region claim independence but are recognized as such by only a handful or by no independent states, Nagorno-Karabakh, Abkhazia and South Ossetia. Abkhazia and South Ossetia are recognised by the majority of independent states as part of Georgia, the Russian divisions include Krasnodar Krai, Stavropol Krai, and the autonomous republics of Adygea, Karachay–Cherkessia, Kabardino-Balkaria, North Ossetia, Ingushetia, Chechnya, and Dagestan. The region has many different languages and language families, there are more than 50 ethnic groups living in the region. Russian is used as a common language, today the peoples of the Northern and Southern Caucasus tend to be either Eastern Orthodox Christians, Oriental Orthodox Christians, or Sunni Muslims. Shia Islam has had many adherents historically in Azerbaijan, located in the part of the region. Located on the peripheries of Turkey, Iran, and Russia, the region has been an arena for political, military, religious, throughout its history, the Caucasus was usually incorporated into the Iranian world
Caucasus
–
Caucasus from the sea by
Ivan Aivazovsky, 1899
Caucasus
–
Caucasus mountain range
Caucasus
–
View of the Caucasus Mountains in
Dagestan, Russia
Caucasus
–
Petroglyphs in
Gobustan,
Azerbaijan, dating back to 10,000 BC indicating a thriving culture. It is a
UNESCO World Heritage Site.
26.
Mauritania
–
Mauritania /mɔːrɪˈteɪniə/, officially the Islamic Republic of Mauritania, is a country in the Maghreb region of western Africa. The country derives its name from the ancient Berber Kingdom of Mauretania, approximately 90% of Mauritanias land is within the Sahara and consequently the population is concentrated in the south, where precipitation is slightly higher. The capital and largest city is Nouakchott, located on the Atlantic coast, the government was overthrown on 6 August 2008, in a military coup détat led by General Mohamed Ould Abdel Aziz. On 16 April 2009, Aziz resigned from the military to run for president in the 19 July elections, about 20% of Mauritanians live on less than US$1.25 per day. Mauritania suffers from several human rights issues, including slavery, as at least 4% of the population are enslaved against their will, the Bafours were primarily agriculturalist, and among the first Saharan people to abandon their historically nomadic lifestyle. With the gradual desiccation of the Sahara, they headed south, many of the Berber tribes claimed Yemeni origins. There is little evidence to such claims, but a 2000 DNA study of Yemeni people suggested there might be some ancient connection between the peoples. Other peoples also migrated south past the Sahara to West Africa, in 1076, Moorish Islamic warrior monks attacked and conquered the large area of the ancient Ghana Empire. Over the next 500 years, Arabs overcame fierce resistance from the population to dominate Mauritania. The Char Bouba war was the final effort of the peoples to repel the Yemeni Maqil Arab invaders. The invaders were led by the Beni Hassan tribe, the descendants of the Beni Hassan warriors became the upper stratum of Moorish society. Hassaniya, a Berber-influenced Arabic dialect that derives its name from the Beni Hassan, berbers retained a niche influence by producing the majority of the regions marabouts, those who preserve and teach Islamic tradition. Imperial France gradually absorbed the territories of present-day Mauritania from the Senegal River area and upwards, in 1901, Xavier Coppolani took charge of the imperial mission. Through a combination of strategic alliances with Zawiya tribes, and military pressure on the Hassane warrior nomads, he managed to extend French rule over the Mauritanian emirates. Trarza, Brakna and Tagant quickly submitted to treaties with the colonial power, Adrar was finally defeated militarily in 1912, and incorporated into the territory of Mauritania, which had been drawn up and planned in 1904. Mauritania was part of French West Africa from 1920, French rule brought legal prohibitions against slavery and an end to inter-clan warfare. During the colonial period, 90% of the population remained nomadic, many sedentary peoples, whose ancestors had been expelled centuries earlier, began to trickle back into Mauritania. After gaining independence, larger numbers of indigenous Sub-Saharan African peoples entered Mauritania, educated in French language and customs, many of these recent arrivals became clerks, soldiers, and administrators in the new state
Mauritania
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The
Dutch trading post of
Arguin in 1665
Mauritania
Mauritania
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Chinguetti was a center of Islamic scholarship in West Africa.
Mauritania
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Road from Nouakchott to the Mauritanian–Senegalese border
27.
Middle Ages
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In the history of Europe, the Middle Ages or Medieval Period lasted from the 5th to the 15th century. It began with the fall of the Western Roman Empire and merged into the Renaissance, the Middle Ages is the middle period of the three traditional divisions of Western history, classical antiquity, the medieval period, and the modern period. The medieval period is subdivided into the Early, High. Population decline, counterurbanisation, invasion, and movement of peoples, the large-scale movements of the Migration Period, including various Germanic peoples, formed new kingdoms in what remained of the Western Roman Empire. In the seventh century, North Africa and the Middle East—once part of the Byzantine Empire—came under the rule of the Umayyad Caliphate, although there were substantial changes in society and political structures, the break with classical antiquity was not complete. The still-sizeable Byzantine Empire survived in the east and remained a major power, the empires law code, the Corpus Juris Civilis or Code of Justinian, was rediscovered in Northern Italy in 1070 and became widely admired later in the Middle Ages. In the West, most kingdoms incorporated the few extant Roman institutions, monasteries were founded as campaigns to Christianise pagan Europe continued. The Franks, under the Carolingian dynasty, briefly established the Carolingian Empire during the later 8th, the Crusades, first preached in 1095, were military attempts by Western European Christians to regain control of the Holy Land from Muslims. Kings became the heads of centralised nation states, reducing crime and violence, intellectual life was marked by scholasticism, a philosophy that emphasised joining faith to reason, and by the founding of universities. Controversy, heresy, and the Western Schism within the Catholic Church paralleled the conflict, civil strife. Cultural and technological developments transformed European society, concluding the Late Middle Ages, the Middle Ages is one of the three major periods in the most enduring scheme for analysing European history, classical civilisation, or Antiquity, the Middle Ages, and the Modern Period. Medieval writers divided history into periods such as the Six Ages or the Four Empires, when referring to their own times, they spoke of them as being modern. In the 1330s, the humanist and poet Petrarch referred to pre-Christian times as antiqua, leonardo Bruni was the first historian to use tripartite periodisation in his History of the Florentine People. Bruni and later argued that Italy had recovered since Petrarchs time. The Middle Ages first appears in Latin in 1469 as media tempestas or middle season, in early usage, there were many variants, including medium aevum, or middle age, first recorded in 1604, and media saecula, or middle ages, first recorded in 1625. The alternative term medieval derives from medium aevum, tripartite periodisation became standard after the German 17th-century historian Christoph Cellarius divided history into three periods, Ancient, Medieval, and Modern. The most commonly given starting point for the Middle Ages is 476, for Europe as a whole,1500 is often considered to be the end of the Middle Ages, but there is no universally agreed upon end date. English historians often use the Battle of Bosworth Field in 1485 to mark the end of the period
Middle Ages
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The
Cross of Mathilde, a
crux gemmata made for
Mathilde, Abbess of Essen (973–1011), who is shown kneeling before the Virgin and Child in the
enamel plaque. The body of Christ is slightly later. Probably made in
Cologne or
Essen, the cross demonstrates several medieval techniques:
cast figurative sculpture,
filigree, enamelling, gem polishing and setting, and the reuse of Classical
cameos and
engraved gems.
Middle Ages
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A late Roman statue
depicting the four Tetrarchs, now in
Venice
Middle Ages
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Coin of
Theodoric
Middle Ages
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Mosaic showing
Justinian with
the bishop of
Ravenna, bodyguards, and courtiers
28.
Ultramarine
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Ultramarine is a deep blue color and a pigment which was originally made by grinding lapis lazuli into a powder. The name comes from the Latin ultramarinus, literally beyond the sea, Ultramarine was the finest and most expensive blue used by Renaissance painters. It was often used for the robes of the Virgin Mary and it remained an extremely expensive pigment until a synthetic ultramarine was invented in 1826. The pigment consists primarily of a mineral containing small amounts of polysulfides. It occurs in nature as a component of lapis lazuli containing a blue cubic mineral called lazurite. The pigment color code is P, the major component of lazurite is a complex sulfur-containing sodium-silicate, which makes ultramarine the most complex of all mineral pigments. Some chloride is present in the crystal lattice as well. The blue color of the pigment is due to the S−3 radical anion, the preparation is typically made in steps. The first part of the takes place at 700 to 750 °C in a closed furnace, so that sulphur, carbon. This yields a yellow-green product sometimes used as a pigment, in the second step air or sulphur dioxide at 350 to 450 °C is used to oxidise sulphide sulphur in the intermediate product to S2 and Sn chromophore molecules, resulting in the blue pigment. The mixture is heated in a kiln, sometimes in brick-sized amounts, the resultant solids are then ground and washed as per any other insoluble pigment manufacturing process. The chemical reaction produces large amounts of sulfur dioxide, meaning that flue-gas desulfurization is an part of its manufacture to comply with pollution regulations. Large chimneys were used to disperse sulfur dioxide produced in the process, resulting in ultramarine tinting the surrounding ground surfaces, Ultramarine poor in silica is obtained by fusing a mixture of soft clay, sodium sulfate, charcoal, sodium carbonate and sulfur. The product is at first white, but soon turns green green ultramarine when it is mixed with sulfur, the sulfur burns, and a fine blue pigment is obtained. Ultramarine rich in silica is obtained by heating a mixture of pure clay, very fine white sand, sulfur. A blue product is obtained at once, but a red tinge often results, the different ultramarines—green, blue, red and violet—are finely ground and washed with water. Its color is unaffected by light nor by contact with oil or lime as used in painting, hydrochloric acid immediately bleaches it with liberation of hydrogen sulfide. Even a small addition of oxide to the reddish varieties especially causes a considerable diminution in the intensity of the color
Ultramarine
–
Synthetic ultramarine
pigment
Ultramarine
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Lapis lazuli specimen (rough), Afghanistan
Ultramarine
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Natural ultramarine
Ultramarine
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Synthetic ultramarine violet
29.
Pigment
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A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, many materials selectively absorb certain wavelengths of light. Materials that humans have chosen and developed for use as pigments usually have properties that make them ideal for coloring other materials. A pigment must have a high tinting strength relative to the materials it colors and it must be stable in solid form at ambient temperatures. For industrial applications, as well as in the arts, permanence, pigments that are not permanent are called fugitive. Fugitive pigments fade over time, or with exposure to light, pigments are used for coloring paint, ink, plastic, fabric, cosmetics, food, and other materials. Most pigments used in manufacturing and the arts are dry colorants. This powder is added to a binder, a neutral or colorless material that suspends the pigment. A distinction is made between a pigment, which is insoluble in its vehicle, and a dye, which either is itself a liquid or is soluble in its vehicle. A colorant can act as either a pigment or a dye depending on the vehicle involved, in some cases, a pigment can be manufactured from a dye by precipitating a soluble dye with a metallic salt. The resulting pigment is called a lake pigment, the term biological pigment is used for all colored substances independent of their solubility. In 2006, around 7.4 million tons of inorganic, organic, asia has the highest rate on a quantity basis followed by Europe and North America. By 2020, revenues will have risen to approx, the global demand on pigments was roughly US$20.5 billion in 2009, around 1. 5-2% up from the previous year. It is predicted to increase in a growth rate in the coming years. The worldwide sales are said to increase up to US$24.5 billion in 2015, pigments appear the colors they are because they selectively reflect and absorb certain wavelengths of visible light. White light is an equal mixture of the entire spectrum of visible light with a wavelength in a range from about 375 or 400 nanometers to about 760 or 780 nm. When this light encounters a pigment, parts of the spectrum are absorbed by the molecules or ions of the pigment, in organic pigments such as diazo or phthalocyanine compounds the light is absorbed by the conjugated systems of double bonds in the molecule. Some of the inorganic pigments such as vermilion or cadmium yellow absorb light by transferring an electron from the ion to the positive ion
Pigment
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Natural
ultramarine pigment in powdered form
Pigment
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Synthetic ultramarine pigment is chemically identical to natural ultramarine
Pigment
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Miracle of the Slave by
Tintoretto (c. 1548). The son of a master
dyer, Tintoretto used Carmine Red Lake pigment, derived from the
cochineal insect, to achieve dramatic color effects.
Pigment
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Girl with a Pearl Earring by
Johannes Vermeer (c. 1665).
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