Portal:Minerals

The Minerals Portal

In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.

The geological definition of mineral normally excludes compounds that occur only in living organisms. However, some minerals are often biogenic (such as calcite) or chemically organic compounds (such as mellite). Moreover, living organisms often synthesize inorganic minerals (such as hydroxylapatite) that also occur in rocks.

The concept of mineral is distinct from rock, which is any bulk solid geologic material that is relatively homogeneous at a large enough scale. A rock may consist of one type of mineral or may be an aggregate of two or more different types of minerals, spacially segregated into distinct phases.

Some natural solid substances without a definite crystalline structure, such as opal or obsidian, are more properly called mineraloids. If a chemical compound occurs naturally with different crystal structures, each structure is considered a different mineral species. Thus, for example, quartz and stishovite are two different minerals consisting of the same compound, silicon dioxide. (Full article...)

Mineralogy is a subject of geology specializing in the scientific study of the chemistry, crystal structure, and physical (including optical) properties of minerals and mineralized artifacts. Specific studies within mineralogy include the processes of mineral origin and formation, classification of minerals, their geographical distribution, and their utilization. (Full article...)

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$Image 1 Cinnabar, Staatliches Museum für Naturkunde Karlsruhe, Germany Cinnabar (/ˈsɪnəˌbɑːr/; from Ancient Greek κιννάβαρι (kinnábari)), also called cinnabarite (/ˌsɪnəˈbɑːraɪt/) or mercurblende, is the bright scarlet to brick-red form of mercury(II) sulfide (HgS). It is the most common source ore for refining elemental mercury and is the historic source for the brilliant red or scarlet pigment termed vermilion and associated red mercury pigments. Cinnabar generally occurs as a vein-filling mineral associated with volcanic activity and alkaline hot springs. The mineral resembles quartz in symmetry and it exhibits birefringence. Cinnabar has a mean refractive index near 3.2, a hardness between 2.0 and 2.5, and a specific gravity of approximately 8.1. The color and properties derive from a structure that is a hexagonal crystalline lattice belonging to the trigonal crystal system, crystals that sometimes exhibit twinning. Cinnabar has been used for its color since antiquity in the Near East, including as a rouge-type cosmetic, in the New World since the Olmec culture, and in China since as early as the Yangshao culture, where it was used in coloring stoneware. In Roman times, cinnabar was highly valued as paint for walls, especially interiors, since it darkened when used outdoors due to exposure to sunlight. Associated modern precautions for the use and handling of cinnabar arise from the toxicity of the mercury component. (Full article...)$

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Cinnabar, Staatliches Museum für Naturkunde Karlsruhe, Germany

Cinnabar (/ˈsɪnəˌbɑːr/; from Ancient Greek κιννάβαρι (kinnábari)), also called cinnabarite (/ˌsɪnəˈbɑːraɪt/) or mercurblende, is the bright scarlet to brick-red form of mercury(II) sulfide (HgS). It is the most common source ore for refining elemental mercury and is the historic source for the brilliant red or scarlet pigment termed vermilion and associated red mercury pigments.

Cinnabar generally occurs as a vein-filling mineral associated with volcanic activity and alkaline hot springs. The mineral resembles quartz in symmetry and it exhibits birefringence. Cinnabar has a mean refractive index near 3.2, a hardness between 2.0 and 2.5, and a specific gravity of approximately 8.1. The color and properties derive from a structure that is a hexagonal crystalline lattice belonging to the trigonal crystal system, crystals that sometimes exhibit twinning.

Cinnabar has been used for its color since antiquity in the Near East, including as a rouge-type cosmetic, in the New World since the Olmec culture, and in China since as early as the Yangshao culture, where it was used in coloring stoneware. In Roman times, cinnabar was highly valued as paint for walls, especially interiors, since it darkened when used outdoors due to exposure to sunlight.

Associated modern precautions for the use and handling of cinnabar arise from the toxicity of the mercury component. (Full article...)
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Turquoise is an opaque, blue-to-green mineral that is a hydrous phosphate of copper and aluminium, with the chemical formula Cu Al₆(PO₄)₄(OH)₈·4H₂O. It is rare and valuable in finer grades and has been prized as a gemstone for millennia due to its hue.

The robin egg blue or sky blue color of the Persian turquoise mined near the modern city of Nishapur, Iran, has been used as a guiding reference for evaluating turquoise quality.

Like most other opaque gems, turquoise has been devalued by the introduction of treatments, imitations, and synthetics into the market. (Full article...)
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Gypsum from southwest France (27 × 22 cm)

Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO₄·2H₂O. It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, drywall and blackboard or sidewalk chalk. Gypsum also crystallizes as translucent crystals of selenite. It forms as an evaporite mineral and as a hydration product of anhydrite. The Mohs scale of mineral hardness defines gypsum as hardness value 2 based on scratch hardness comparison.

Fine-grained white or lightly tinted forms of gypsum known as alabaster have been used for sculpture by many cultures including Ancient Egypt, Mesopotamia, Ancient Etruscans, Ancient Rome, the Byzantine Empire, and the Nottingham alabasters of Medieval England. (Full article...)
$Image 4 Malachite from the Democratic Republic of the Congo Malachite (/ˈmæl.əˌkaɪt/) is a copper carbonate hydroxide mineral, with the formula Cu2CO3(OH)2. This opaque, green-banded mineral crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagmitic masses, in fractures and deep, underground spaces, where the water table and hydrothermal fluids provide the means for chemical precipitation. Individual crystals are rare, but occur as slender to acicular prisms. Pseudomorphs after more tabular or blocky azurite crystals also occur. (Full article...)$

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Malachite from the Democratic Republic of the Congo

Malachite (/ˈmæl.əˌkaɪt/) is a copper carbonate hydroxide mineral, with the formula Cu₂CO₃(OH)₂. This opaque, green-banded mineral crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagmitic masses, in fractures and deep, underground spaces, where the water table and hydrothermal fluids provide the means for chemical precipitation. Individual crystals are rare, but occur as slender to acicular prisms. Pseudomorphs after more tabular or blocky azurite crystals also occur. (Full article...)
$Image 5 A rough diamond Diamond is a mineral form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Diamond is a tasteless, odorless, strong, brittle solid, a poor conductor of electricity, colorless in pure form, and insoluble in water. Another solid form of carbon known as graphite is the chemically stable form of carbon at room temperature and pressure, but diamond is metastable and converts to it at a negligible rate under those conditions. Diamond has the highest hardness and thermal conductivity of any natural material, properties that are used in major industrial applications such as cutting and polishing tools. Because the arrangement of atoms in diamond is extremely rigid, few types of impurity can contaminate it (two exceptions are boron and nitrogen). Small numbers of defects or impurities—about one per million of lattice atoms—can color a diamond blue (boron), yellow (nitrogen), brown (defects), green (radiation exposure), purple, pink, orange, or red. Diamond also has a very high refractive index and a relatively high optical dispersion. Most natural diamonds have ages between 1 billion and 3.5 billion years. Most were formed at depths between 150 and 250 kilometres (93 and 155 mi) in the Earth's mantle, although a few have come from as deep as 800 kilometres (500 mi). Under high pressure and temperature, carbon-containing fluids dissolved various minerals and replaced them with diamonds. Much more recently (hundreds to tens of million years ago), they were carried to the surface in volcanic eruptions and deposited in igneous rocks known as kimberlites and lamproites. Synthetic diamonds can be grown from high-purity carbon under high pressures and temperatures or from hydrocarbon gases by chemical vapor deposition (CVD). Natural and synthetic diamonds are most commonly distinguished using optical techniques or thermal conductivity measurements. (Full article...)$

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A rough diamond

Diamond is a mineral form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Diamond is a tasteless, odorless, strong, brittle solid, a poor conductor of electricity, colorless in pure form, and insoluble in water. Another solid form of carbon known as graphite is the chemically stable form of carbon at room temperature and pressure, but diamond is metastable and converts to it at a negligible rate under those conditions. Diamond has the highest hardness and thermal conductivity of any natural material, properties that are used in major industrial applications such as cutting and polishing tools.

Because the arrangement of atoms in diamond is extremely rigid, few types of impurity can contaminate it (two exceptions are boron and nitrogen). Small numbers of defects or impurities—about one per million of lattice atoms—can color a diamond blue (boron), yellow (nitrogen), brown (defects), green (radiation exposure), purple, pink, orange, or red. Diamond also has a very high refractive index and a relatively high optical dispersion.

Most natural diamonds have ages between 1 billion and 3.5 billion years. Most were formed at depths between 150 and 250 kilometres (93 and 155 mi) in the Earth's mantle, although a few have come from as deep as 800 kilometres (500 mi). Under high pressure and temperature, carbon-containing fluids dissolved various minerals and replaced them with diamonds. Much more recently (hundreds to tens of million years ago), they were carried to the surface in volcanic eruptions and deposited in igneous rocks known as kimberlites and lamproites.

Synthetic diamonds can be grown from high-purity carbon under high pressures and temperatures or from hydrocarbon gases by chemical vapor deposition (CVD). Natural and synthetic diamonds are most commonly distinguished using optical techniques or thermal conductivity measurements. (Full article...)
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Kaolinite (/ˈkeɪ.ələˌnaɪt, -lɪ-/ KAY-ə-lə-nyte, -⁠lih-; also called kaolin) is a clay mineral, with the chemical composition Al₂Si₂O₅(OH)₄. It is a layered silicate mineral, with one "tetrahedral" sheet of silicate tetrahedra (SiO₄) linked to one "octahedral" sheet of aluminate octahedrons (AlO₂(OH)₄) through oxygen atoms on one side, and another such sheet through hydrogen bonds on the other side.

Kaolinite is a soft, earthy, usually white, mineral (dioctahedral phyllosilicate clay), produced by the chemical weathering of aluminium silicate minerals like feldspar. It has a low shrink–swell capacity and a low cation-exchange capacity (1–15 meq/100 g).

Rocks that are rich in kaolinite, and halloysite, are known as kaolin (/ˈkeɪ.əlɪn/) or china clay. In many parts of the world kaolin is colored pink-orange-red by iron oxide, giving it a distinct rust hue. Lower concentrations of iron oxide yield the white, yellow, or light orange colors of kaolin. Alternating lighter and darker layers are sometimes found, as at Providence Canyon State Park in Georgia, United States.

Kaolin is an important raw material in many industries and applications. Commercial grades of kaolin are supplied and transported as powder, lumps, semi-dried noodle or slurry. Global production of kaolin in 2021 was estimated to be 45 million tonnes, with a total market value of US $4.24 billion. (Full article...)
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Mineralogy applies principles of chemistry, geology, physics and materials science to the study of minerals

Mineralogy is a subject of geology specializing in the scientific study of the chemistry, crystal structure, and physical (including optical) properties of minerals and mineralized artifacts. Specific studies within mineralogy include the processes of mineral origin and formation, classification of minerals, their geographical distribution, and their utilization. (Full article...)
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Tourmaline (/ˈtʊərməlɪn, -ˌliːn/ TOOR-mə-lin, -⁠leen) is a crystalline silicate mineral group in which boron is compounded with elements such as aluminium, iron, magnesium, sodium, lithium, or potassium. This gemstone comes in a wide variety of colors.

The name is derived from the Sinhalese tōramalli (ටෝරමල්ලි), which refers to the carnelian gemstones. (Full article...)
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A rock containing three crystals of pyrite (FeS₂). The crystal structure of pyrite is primitive cubic, and this is reflected in the cubic symmetry of its natural crystal facets.

In crystallography, the cubic (or isometric) crystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals.

There are three main varieties of these crystals:
- Primitive cubic (abbreviated cP and alternatively called simple cubic)
- Body-centered cubic (abbreviated cI or bcc)
- Face-centered cubic (abbreviated cF or fcc)
Note: the term fcc is often used synonymously for the cubic close-packed or ccp structure occurring in metals. However, fcc stands for a face-centered cubic Bravais lattice, which is not necessarily close-packed when a motif is set onto the lattice points. E.g. the diamond and the zincblende lattices are fcc but not close-packed.
Each is subdivided into other variants listed below. Although the unit cells in these crystals are conventionally taken to be cubes, the primitive unit cells often are not. (Full article...)
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Frameworks of LTA-type (left) and FAU-type zeolites (right)

Zeolites are a group of several microporous, crystalline aluminosilicate minerals commonly used as commercial adsorbents and catalysts. They mainly consist of silicon, aluminium, and oxygen, and have the general formula Mⁿ⁺
_1/n(AlO
₂)⁻
(SiO
₂)
_x･yH
₂O where Mⁿ⁺
_1/n is either a metal ion or H⁺.

The term was originally coined in 1756 by Swedish mineralogist Axel Fredrik Cronstedt, who observed that rapidly heating a material, believed to have been stilbite, produced large amounts of steam from water that had been adsorbed by the material. Based on this, he called the material zeolith (changed later to zeolite in English, to fit the naming scheme for minerals in -ite) from the Greek ζέω (zéō), meaning "to boil" and λίθος (líthos), meaning "stone". (Full article...)
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The diamond crystal structure belongs to the face-centered cubic lattice, with a repeated two-atom pattern.

In crystallography, a crystal system is a set of point groups (a group of geometric symmetries with at least one fixed point). A lattice system is a set of Bravais lattices (an infinite array of discrete points). Space groups (symmetry groups of a configuration in space) are classified into crystal systems according to their point groups, and into lattice systems according to their Bravais lattices. Crystal systems that have space groups assigned to a common lattice system are combined into a crystal family.

The seven crystal systems are triclinic, monoclinic, orthorhombic, tetragonal, trigonal, hexagonal, and cubic. Informally, two crystals are in the same crystal system if they have similar symmetries (though there are many exceptions). (Full article...)
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Borax (also referred to as sodium borate, tincal (/ˈtɪŋkəl/) and tincar (/ˈtɪŋkər/)) is a salt (ionic compound) normally encountered as a hydrated borate of sodium, with the chemical formula Na₂H₂₀B₄O₁₇. Borax mineral is a crystalline borate mineral that occurs in only a few places worldwide in quantities that enable it to be mined economically.

Borax can be dehydrated by heating into other forms with less water of hydration. The anhydrous form of borax can also be obtained from the decahydrate or other hydrates by heating and then grinding the resulting glasslike solid into a powder. It is a white crystalline solid that dissolves in water to make a basic solution due to the tetraborate anion.

Borax is commonly available in powder or granular form and has many industrial and household uses, including as a pesticide, as a metal soldering flux, as a component of glass, enamel, and pottery glazes, for tanning of skins and hides, for artificial aging of wood, as a preservative against wood fungus, as a food additive, and as a pharmaceutic alkalizer. In chemical laboratories it is used as a buffering agent.

The terms tincal and tincar refer to the naturally occurring borax historically mined from dry lake beds in various parts of Asia. (Full article...)
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A ruby crystal from Dodoma Region, Tanzania

Ruby is a pinkish-red to blood-red-colored gemstone, a variety of the mineral corundum, consisting of aluminium oxide (α-Al₂O₃). Ruby is one of the most popular traditional jewelry gems and is very durable. Other varieties of gem-quality corundum are called sapphires, and rubies are also sometimes referred to as "red sapphires".

Ruby is one of the traditional cardinal gems, alongside amethyst, sapphire, emerald, and diamond. The word ruby comes from ruber, Latin for red. The color of a ruby is due to the presence of chromium.

Some gemstones that are popularly or historically called rubies, such as the Black Prince's Ruby in the British Imperial State Crown, are actually spinels. These were once known as "Balas rubies".

The quality of a ruby is determined by its color, cut, and clarity, which, along with carat weight, affect its value. The brightest and most valuable shade of red, called blood-red or pigeon blood, commands a large premium over other rubies of similar quality. After color comes clarity: similar to diamonds, a clear stone will command a premium, but a ruby without any needle-like rutile inclusions may indicate that the stone has been treated. Ruby is the traditional birthstone for July and is usually pinker than garnet, although some rhodolite garnets have a similar pinkish hue to most rubies. The world's most valuable ruby to be sold at auction is the Estrela de Fura, which sold for US$34.8 million. (Full article...)
$Image 14 A rich seam of iridescent opal encased in matrix Opal is a hydrated amorphous form of silica (SiO2·nH2O); its water content may range from 3% to 21% by weight, but is usually between 6% and 10%. Due to the amorphous (chemical) physical structure, it is classified as a mineraloid, unlike crystalline forms of silica, which are considered minerals. It is deposited at a relatively low temperature and may occur in the fissures of almost any kind of rock, being most commonly found with limonite, sandstone, rhyolite, marl, and basalt. The name opal is believed to be derived from the Sanskrit word upala (उपल), which means 'jewel', and later the Greek derivative opállios (ὀπάλλιος). There are two broad classes of opal: precious and common. Precious opal displays play-of-color (iridescence); common opal does not. Play-of-color is defined as "a pseudo chromatic optical effect resulting in flashes of colored light from certain minerals, as they are turned in white light." The internal structure of precious opal causes it to diffract light, resulting in play-of-color. Depending on the conditions in which it formed, opal may be transparent, translucent, or opaque, and the background color may be white, black, or nearly any color of the visual spectrum. Black opal is considered the rarest, while white, gray, and green opals are the most common. (Full article...)$

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A rich seam of iridescent opal encased in matrix

Opal is a hydrated amorphous form of silica (SiO₂·nH₂O); its water content may range from 3% to 21% by weight, but is usually between 6% and 10%. Due to the amorphous (chemical) physical structure, it is classified as a mineraloid, unlike crystalline forms of silica, which are considered minerals. It is deposited at a relatively low temperature and may occur in the fissures of almost any kind of rock, being most commonly found with limonite, sandstone, rhyolite, marl, and basalt.

The name opal is believed to be derived from the Sanskrit word upala (उपल), which means 'jewel', and later the Greek derivative opállios (ὀπάλλιος).

There are two broad classes of opal: precious and common. Precious opal displays play-of-color (iridescence); common opal does not. Play-of-color is defined as "a pseudo chromatic optical effect resulting in flashes of colored light from certain minerals, as they are turned in white light." The internal structure of precious opal causes it to diffract light, resulting in play-of-color. Depending on the conditions in which it formed, opal may be transparent, translucent, or opaque, and the background color may be white, black, or nearly any color of the visual spectrum. Black opal is considered the rarest, while white, gray, and green opals are the most common. (Full article...)
$Image 15 Talc, or talcum, is a clay mineral composed of hydrated magnesium silicate, with the chemical formula Mg3Si4O10(OH)2. Talc in powdered form, often combined with corn starch, is used as baby powder. This mineral is used as a thickening agent and lubricant. It is an ingredient in ceramics, paints, and roofing material. It is a main ingredient in many cosmetics. It occurs as foliated to fibrous masses, and in an exceptionally rare crystal form. It has a perfect basal cleavage and an uneven flat fracture, and it is foliated with a two-dimensional platy form. The Mohs scale of mineral hardness, based on scratch hardness comparison, defines value 1 as the hardness of talc, the softest mineral. When scraped on a streak plate, talc produces a white streak, though this indicator is of little importance, because most silicate minerals produce a white streak. Talc is translucent to opaque, with colors ranging from whitish grey to green with a vitreous and pearly luster. Talc is not soluble in water, and is slightly soluble in dilute mineral acids. Soapstone is a metamorphic rock composed predominantly of talc. (Full article...)$

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Talc, or talcum, is a clay mineral composed of hydrated magnesium silicate, with the chemical formula Mg₃Si₄O₁₀(OH)₂. Talc in powdered form, often combined with corn starch, is used as baby powder. This mineral is used as a thickening agent and lubricant. It is an ingredient in ceramics, paints, and roofing material. It is a main ingredient in many cosmetics. It occurs as foliated to fibrous masses, and in an exceptionally rare crystal form. It has a perfect basal cleavage and an uneven flat fracture, and it is foliated with a two-dimensional platy form.

The Mohs scale of mineral hardness, based on scratch hardness comparison, defines value 1 as the hardness of talc, the softest mineral. When scraped on a streak plate, talc produces a white streak, though this indicator is of little importance, because most silicate minerals produce a white streak. Talc is translucent to opaque, with colors ranging from whitish grey to green with a vitreous and pearly luster. Talc is not soluble in water, and is slightly soluble in dilute mineral acids.

Soapstone is a metamorphic rock composed predominantly of talc. (Full article...)
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Three varieties of beryl (left to right): morganite, aquamarine and emerald

Beryl (/ˈbɛrəl/ BERR-əl) is a mineral composed of beryllium aluminium silicate with the chemical formula Be₃Al₂(SiO₃)₆. Well-known varieties of beryl include emerald and aquamarine. Naturally occurring hexagonal crystals of beryl can be up to several meters in size, but terminated crystals are relatively rare. Pure beryl is colorless, but it is frequently tinted by impurities; possible colors are green, blue, yellow, pink, and red (the rarest). It is an ore source of beryllium. (Full article...)
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Dolomite (white) on talc

Dolomite (/ˈdɒl.əˌmaɪt, ˈdoʊ.lə-/) is an anhydrous carbonate mineral composed of calcium magnesium carbonate, ideally CaMg(CO₃)₂. The term is also used for a sedimentary carbonate rock composed mostly of the mineral dolomite (see Dolomite (rock)). An alternative name sometimes used for the dolomitic rock type is dolostone. (Full article...)
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Beachy Head is a part of the extensive Southern England Chalk Formation.

Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed under the sea by the accumulation and lithification of hard parts of organisms, mostly microscopic plankton, which had settled to the sea floor. Chalk is common throughout Western Europe, where deposits underlie parts of France, and steep cliffs are often seen where they meet the sea in places such as the Dover cliffs on the Kent coast of the English Channel.

Chalk is mined for use in industry, such as for quicklime, bricks and builder's putty, and in agriculture, for raising pH in soils with high acidity. It is also used for "blackboard chalk" for writing and drawing on various types of surfaces, although these can also be manufactured from other carbonate-based minerals or gypsum. (Full article...)
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Corundum is a crystalline form of aluminium oxide (Al₂O₃) typically containing traces of iron, titanium, vanadium, and chromium. It is a rock-forming mineral. It is a naturally transparent material, but can have different colors depending on the presence of transition metal impurities in its crystalline structure. Corundum has two primary gem varieties: ruby and sapphire. Rubies are red due to the presence of chromium, and sapphires exhibit a range of colors depending on what transition metal is present. A rare type of sapphire, padparadscha sapphire, is pink-orange.

The name "corundum" is derived from the Tamil-Dravidian word kurundam (ruby-sapphire) (appearing in Sanskrit as kuruvinda).

Because of corundum's hardness (pure corundum is defined to have 9.0 on the Mohs scale), it can scratch almost all other minerals. Emery, a variety of corundum with no value as a gemstone, is commonly used as an abrasive on sandpaper and on large tools used in machining metals, plastics, and wood. It is a black granular form of corundum, in which the mineral is intimately mixed with magnetite, hematite, or hercynite.

In addition to its hardness, corundum has a density of 4.02 g/cm³ (251 lb/cu ft), which is unusually high for a transparent mineral composed of the low-atomic mass elements aluminium and oxygen. (Full article...)
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Fibrous tremolite asbestos on muscovite

Asbestos or asbestus (/æsˈbɛstəs, æz-, -tɒs/ ass-BES-təs, az-, -⁠toss) is a group of naturally occurring, fibrous silicate minerals that have been used for thousands of years to create flexible fire-resistant objects, such as fireproof fabrics. It is toxic and carcinogenic.

There are six types, all of which are composed of long and thin fibrous crystals, with each fibre (particulate with length substantially greater than width) composed of many microscopic "fibrils" that can be released into the atmosphere by abrasion and other processes. Inhalation of asbestos fibres can lead to various dangerous lung conditions, including mesothelioma, asbestosis, and lung cancer. As a result of these health effects, asbestos is considered a serious health and safety hazard.

Archaeological studies have found evidence of asbestos being used as far back as the Stone Age to strengthen ceramic pots, but large-scale mining began at the end of the 19th century when manufacturers and builders began using asbestos for its desirable physical properties. Asbestos is an excellent thermal and electrical insulator, and is highly fire-resistant, so for much of the 20th century, it was very commonly used around the world as a building material (particularly for its fire-retardant properties), until its adverse effects on human health were more widely recognized and acknowledged in the 1970s. Many buildings constructed before the 1980s contain asbestos.

The use of asbestos for construction and fireproofing has been made illegal in many countries. Despite this, around 255,000 people are thought to die each year from diseases related to asbestos exposure. In part, this is because many older buildings still contain asbestos; in addition, the consequences of exposure can take decades to arise. The latency period (from exposure until the diagnosis of negative health effects) is typically 20 years. The most common diseases associated with chronic asbestos exposure are asbestosis (scarring of the lungs due to asbestos inhalation) and mesothelioma (a type of cancer). (Full article...)
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Chalcopyrite (/ˌkælkəˈpaɪˌraɪt, -koʊ-/ KAL-kə-PY-ryte, -⁠koh-) is a copper iron sulfide mineral and the most abundant copper ore mineral. It has the chemical formula CuFeS₂ and crystallizes in the tetragonal system. It has a brassy to golden yellow color and a hardness of 3.5 to 4 on the Mohs scale. Its streak is diagnostic as green-tinged black.

On exposure to air, chalcopyrite tarnishes to a variety of oxides, hydroxides, and sulfates. Associated copper minerals include the sulfides bornite (Cu₅FeS₄), chalcocite (Cu₂S), covellite (CuS), digenite (Cu₉S₅); carbonates such as malachite and azurite, and rarely oxides such as cuprite (Cu₂O). It is rarely found in association with native copper. Chalcopyrite is a conductor of electricity.

Copper can be extracted from chalcopyrite ore using various methods. The two predominant methods are pyrometallurgy and hydrometallurgy, the former being the most commercially viable. (Full article...)
Image 22
Green fluorite with prominent cleavage

Cleavage, in mineralogy and materials science, is the tendency of crystalline materials to split along definite crystallographic structural planes. These planes of relative weakness are a result of the regular locations of atoms and ions in the crystal, which create smooth repeating surfaces that are visible both in the microscope and to the naked eye. If bonds in certain directions are weaker than others, the crystal will tend to split along the weakly bonded planes. These flat breaks are termed "cleavage". The classic example of cleavage is mica, which cleaves in a single direction along the basal pinacoid, making the layers seem like pages in a book. In fact, mineralogists often refer to "books of mica".

Diamond and graphite provide examples of cleavage. Each is composed solely of a single element, carbon. In diamond, each carbon atom is bonded to four others in a tetrahedral pattern with short covalent bonds. The planes of weakness (cleavage planes) in a diamond are in four directions, following the faces of the octahedron. In graphite, carbon atoms are contained in layers in a hexagonal pattern where the covalent bonds are shorter (and thus even stronger) than those of diamond. However, each layer is connected to the other with a longer and much weaker van der Waals bond. This gives graphite a single direction of cleavage, parallel to the basal pinacoid. So weak is this bond that it is broken with little force, giving graphite a slippery feel as layers shear apart. As a result, graphite makes an excellent dry lubricant.

While all single crystals will show some tendency to split along atomic planes in their crystal structure, if the differences between one direction or another are not large enough, the mineral will not display cleavage. Corundum, for example, displays no cleavage. (Full article...)
Image 23

Apatite (purple), on siderite, from Portugal

Apatite is a group of phosphate minerals, usually hydroxyapatite, fluorapatite and chlorapatite, with high concentrations of OH⁻, F⁻ and Cl⁻ ion, respectively, in the crystal. The formula of the admixture of the three most common endmembers is written as Ca₁₀(PO₄)₆(OH,F,Cl)₂, and the crystal unit cell formulae of the individual minerals are written as Ca₁₀(PO₄)₆(OH)₂, Ca₁₀(PO₄)₆F₂ and Ca₁₀(PO₄)₆Cl₂.

The mineral was named apatite by the German geologist Abraham Gottlob Werner in 1786, although the specific mineral he had described was reclassified as fluorapatite in 1860 by the German mineralogist Karl Friedrich August Rammelsberg. Apatite is often mistaken for other minerals. This tendency is reflected in the mineral's name, which is derived from the Greek word ἀπατάω (apatáō), which means to deceive.

As hydroxyapatite, it forms a major part of the teeth and bones of vertebrate animals. (Full article...)
Image 24

A lustrous crystal of zircon perched on a tan matrix of calcite from the Gilgit District of Pakistan

Zircon (/ˈzɜːrkɒn, -kən/) is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Its chemical name is zirconium(IV) silicate, and its corresponding chemical formula is Zr SiO₄. An empirical formula showing some of the range of substitution in zircon is (Zr_1–y, REE_y)(SiO₄)_1–x(OH)_4x–y. Zircon precipitates from silicate melts and has relatively high concentrations of high field strength incompatible elements. For example, hafnium is almost always present in quantities ranging from 1 to 4%. The crystal structure of zircon is tetragonal crystal system. The natural color of zircon varies between colorless, yellow-golden, red, brown, blue, and green.

The name derives from the Persian zargun, meaning "gold-hued". This word is changed into "jargoon", a term applied to light-colored zircons. The English word "zircon" is derived from Zirkon, which is the German adaptation of this word. Yellow, orange, and red zircon is also known as "hyacinth", from the flower hyacinthus, whose name is of Ancient Greek origin. (Full article...)
Image 25
Crystal structure of table salt (sodium in purple, chlorine in green)

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 intrinsic nature of constituent particles to form symmetric patterns that repeat along the principal directions of three-dimensional space in matter.

The smallest group of particles in a material that constitutes this repeating pattern is the unit cell of the structure. The unit cell completely reflects the symmetry and structure of the entire crystal, which is built up by repetitive translation of the unit cell along its principal axes. The translation vectors define the nodes of the Bravais lattice.

The lengths of principal axes/edges, of the unit cell and angles between them are lattice constants, also called lattice parameters or cell parameters. The symmetry properties of a crystal are described by the concept of space groups. All possible symmetric arrangements of particles in three-dimensional space may be described by 230 space groups.

The crystal structure and symmetry play a critical role in determining many physical properties, such as cleavage, electronic band structure, and optical transparency. (Full article...)

List of selected articles

Selected mineralogist

Image 1

Johan Gottlieb Gahn

Johan Gottlieb Gahn (19 August 1745 – 8 December 1818) was a Swedish chemist and metallurgist who isolated manganese in 1774.

Gahn studied in Uppsala from 1762 to 1770 and became acquainted with chemists Torbern Bergman and Carl Wilhelm Scheele. 1770 he settled in Falun, where he introduced improvements in copper smelting, and participated in building up several factories, including those for vitriol, sulfur and red paint. (Full article...)
$Image 2 Émile Bertrand (1844–1909) was a French mineralogist, in honour of whom bertrandite was named by Alexis Damour. He also gave his name to the Bertrand lens or phase telescope. He studied at the Ecole des Mines in Paris and was a co-founder of the Société française de minéralogie et de cristallographie [fr]. He wrote a book on the application of microscopy to mineralogical studies, "De l'Application du microscope à l'étude de la minéralogie" (1878); published a translation of Ernst Mach's work on the history of mechanics, "La mécanique: exposé historique et critique de son développement" (1904); and is credited with the design of a refractometer. (Full article...)$

Image 2
Émile Bertrand (1844–1909) was a French mineralogist, in honour of whom bertrandite was named by Alexis Damour. He also gave his name to the Bertrand lens or phase telescope.

He studied at the Ecole des Mines in Paris and was a co-founder of the Société française de minéralogie et de cristallographie [fr]. He wrote a book on the application of microscopy to mineralogical studies, "De l'Application du microscope à l'étude de la minéralogie" (1878); published a translation of Ernst Mach's work on the history of mechanics, "La mécanique: exposé historique et critique de son développement" (1904); and is credited with the design of a refractometer. (Full article...)
Image 3
Waldemar Theodore Schaller (August 3, 1882 – September 28, 1967) was an American mineralogist and longtime employee of the United States Geological Survey (USGS). (Full article...)
Image 4
Image of Otto Erdmannsdörffer

Otto Heinrich Erdmannsdörffer (11 March 1876, Heidelberg – 19 April 1955, Heidelberg) was a German mineralogist and petrographer, known for his analysis of rocks and minerals found in the Odenwald, the Black Forest and the Harz Mountains. He was the son of historian Bernhard Erdmannsdörffer.

He studied natural sciences at the universities of Heidelberg and Strasbourg, receiving his doctorate in 1900. For the next twelve years he worked as a research assistant at the Prussian Geological Survey, and in the meantime, obtained his habilitation in mineralogy and petrology from the University of Berlin (1908). In 1912 he was appointed chair of mineralogy and petrology at the Technical University of Hannover, and in 1926 returned to Heidelberg, where he succeeded Ernst Anton Wülfing as director of the mineralogical-petrographic institute. In 1932 he was named academic rector at Heidelberg. (Full article...)
Image 5
Franz Xaver von Wulfen

Franz Xaver Freiherr von Wulfen (5 November 1728 – 17 March 1805) was an Austrian botanist, zoologist, mineralogist, alpinist, and Jesuit priest. He is credited with discovering the flowering plants Wulfenia carinthiaca, Saxifraga moschata, and Stellaria bulbosa. In 1845 the lead molybdate mineral wulfenite was named in his honor by Wilhelm Karl von Haidinger. (Full article...)
Image 6
University of Michigan faculty portrait

Edward Henry Kraus (1 December 1875, Syracuse, NY, US – 1973) was a professor of mineralogy at the University of Michigan and also served as Dean of the Summer Session, 1915–1933, Dean of the College of Pharmacy, 1923–1933, and Dean of the College of Literature, Science and the Arts, 1933–1945. (Full article...)
Image 7
Archibald Bruce (February 1777 – February 22, 1818) was an American physician and mineralogist. (Full article...)
Image 8

Friedel in 1890s

Charles Friedel (French: [ʃaʁl fʁidɛl]; 12 March 1832 – 20 April 1899) was a French chemist and mineralogist. (Full article...)
Image 9

Karl Friedrich August Rammelsberg (1 April 1813 – 28 December 1899) was a German mineralogist from Berlin, Prussia. (Full article...)
Image 10
Walter Flight (21 January 1841 – 4 November 1885), was an English mineralogist who studied the chemical composition of meteorites. He published academic papers on the chemical composition of meteorites in both Germany and the United Kingdom. He also worked for the British Museum, the Royal Military Academy, Woolwich, and on a committee appointed by the British Science Association, then known as the British Association. (Full article...)
Image 11

Photograph by Theodor Hilsdorf (1910)

Paul Heinrich Ritter von Groth (23 June 1843 – 2 December 1927) was a German mineralogist. His most important contribution to science was his systematic classification of minerals based on their chemical compositions and crystal structures. (Full article...)
Image 12
Joseph (Joe) Anthony Mandarino, FRSC (20 April 1929 in Chicago, Illinois – 19 September 2007) was an American-Canadian mineralogist and crystallographer. (Full article...)
Image 13
William James Lewis F.R.S. (10 January 1847 – 16 April 1926) was a Welsh mineralogist. (Full article...)
Image 14
Oskar Alexander Richard Büttner (28 September 1858 – 11 September 1927) was a German botanist and mineralogist who was involved in the exploration of the Congo Basin. (Full article...)
Image 15

William Hallowes Miller

Prof William Hallowes Miller FRS HFRSE LLD DCL (6 April 1801 – 20 May 1880) was a Welsh mineralogist and laid the foundations of modern crystallography.

Miller indices are named after him, the method having been described in his Treatise on Crystallography (1839). The mineral known as millerite is named after him. (Full article...)
Image 16

Leonid Alekseyevich Kulik (Russian: Леонид Алексеевич Кулик; 19 August 1883 – 14 or 24 April 1942) was a Soviet mineralogist who is noted for his research into meteorites. (Full article...)
Image 17
Eugène Louis Melchior Patrin (3 April 1742, Lyon – 15 August 1815, Saint-Vallier) was a French mineralogist and naturalist. His botanical abbreviation is: Patrin.

Following two years of travels in Germany, Hungary and Poland, he spent eight years in Russia (Siberia) (1780–87), conducting geological and botanical investigations. He extensively travelled the Urals, the Altai Mountains and other areas of Siberia, with his mineral collections being shipped back to St. Petersburg ahead of his return. This material, however, was partially confiscated by Pyotr Simon Pallas, who kept the best items for his personal cabinet. Patrin's remaining pieces were subsequently offered to the Jardin du Roi collection in Paris, provided that the group not be broken up. In 1804 he was appointed first librarian of the Conseil des mines. From 1790 to 1815, he was a member of the Académie des sciences, belles-lettres et arts de Lyon. (Full article...)
Image 18
Laminaria bongardiana
by Postels

Alexander Filippovich Postels (Russian: Александр Филиппович Постельс; 24 August 1801 in Dorpat – 28 June 1871 in Vyborg) was a Russian naturalist, mineralogist and artist of Baltic German descent. (Full article...)
Image 19
João da Silva Barbosa or João da Silva Feijó, (1760 in Rio de Janeiro – 1824), was a naturalist, mineralogist and Portuguese soldier, born in Brazil.

João da Silva Feijó studied philosophy and mathematics at the University of Coimbra and adopted the name Feijó in homage to Benito Jerónimo Feijoo, Spanish philosopher, who at the time was respected among natural history students. (Full article...)
Image 20

J. M. Bijvoet in 1931

Johannes Martin Bijvoet (23 January 1892, Amsterdam – 4 March 1980, Winterswijk) was a Dutch chemist and crystallographer at the van 't Hoff Laboratory at Utrecht University. He is famous for devising a method of establishing the absolute configuration of molecules. In 1946, he became member of the Royal Netherlands Academy of Arts and Sciences.

The concept of tetrahedrally bound carbon in organic compounds stems back to the work by van 't Hoff and Le Bel in 1874. At this time, it was impossible to assign the absolute configuration of a molecule by means other than referring to the projection formula established by Fischer, who had used glyceraldehyde as the prototype and assigned randomly its absolute configuration. (Full article...)
Image 21

Ours-Pierre-Armand Petit-Dufrénoy (5 September 1792 – 20 March 1857) was a French geologist and mineralogist. (Full article...)
Image 22
Adam August Krantz (6 December 1808 in Neumarkt in Schlesien – 6 April 1872 in Berlin) was a German mineralogist. (Full article...)
Image 23

Portrait of Edward Salisbury Dana, Yale College Class of 1870

Edward Salisbury Dana (November 16, 1849 – June 16, 1935) was an American mineralogist and physicist. He made important contributions to the study of minerals, especially in the field of crystallography. (Full article...)
Image 24

Axel Hamberg ca. 1910

Axel Hamberg (17 January 1863 – 28 June 1933) was a Swedish mineralogist, geographer and explorer. (Full article...)
Image 25

Arthur Hutchinson by Sir William Rothenstein

Arthur Hutchinson (6 July 1866 – 12 December 1937) was a British mineralogist. During World War I, and at the request of the Admiralty, he was asked to design gas masks suitable for the Navy; for his work, he was awarded the OBE. Hutchinson was elected a Fellow of the Royal Society in 1922. He was master of Pembroke College, Cambridge, from 1928 to 1937, served on the Council of the Royal Society from 1932 to 1934, and was the Society's Vice-President for the year 1933-34. (Full article...)

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... that nine days after his heart transplant, J. C. Walter Jr. merged his company Houston Oil & Minerals with Tenneco, then retired to his ranch and shortly after founded Walter Oil & Gas?

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For editor resources and to collaborate with other editors on improving Wikipedia's Minerals-related articles, see WikiProject Rocks and minerals.

General images

The following are images from various mineral-related articles on Wikipedia.

Image 1Red cinnabar (HgS), a mercury ore, on dolomite. (from Mineral)
Image 2Topaz has a characteristic orthorhombic elongated crystal shape. (from Mineral)
Image 3Carnotite (yellow) is a radioactive uranium-bearing mineral. (from Mineral)
Image 4Natrolite is a mineral series in the zeolite group; this sample has a very prominent acicular crystal habit. (from Mineral)
Image 5Gypsum desert rose (from Mineral)
Image 6Hübnerite, the manganese-rich end-member of the wolframite series, with minor quartz in the background (from Mineral)
Image 7Sphalerite crystal partially encased in calcite from the Devonian Milwaukee Formation of Wisconsin (from Mineral)
Image 8Crystals of serandite, natrolite, analcime, and aegirine from Mont Saint-Hilaire, Quebec, Canada (from Mineral)
Image 9Asbestiform tremolite, part of the amphibole group in the inosilicate subclass (from Mineral)
Image 10Epidote often has a distinctive pistachio-green colour. (from Mineral)
Image 11An example of elbaite, a species of tourmaline, with distinctive colour banding. (from Mineral)
Image 12Mohs Scale versus Absolute Hardness (from Mineral)
Image 13Pyrite has a metallic lustre. (from Mineral)
Image 14Schist is a metamorphic rock characterized by an abundance of platy minerals. In this example, the rock has prominent sillimanite porphyroblasts as large as 3 cm (1.2 in). (from Mineral)
Image 15Pyrite (from Lustre (mineralogy))
Image 16Aegirine, an iron-sodium clinopyroxene, is part of the inosilicate subclass. (from Mineral)
Image 17Mohs scale along the horizontal axis matched with the absolute hardness of each of the Mohs reference-minerals along the vertical; notice that the vertical scale is logarithmic. (from Mohs scale)
Image 18Muscovite, a mineral species in the mica group, within the phyllosilicate subclass (from Mineral)
Image 19Galena, PbS, is a mineral with a high specific gravity. (from Mineral)
Image 20Mohs hardness kit, containing one specimen of each mineral on the ten-point hardness scale (from Mohs scale)
Image 21Diamond is the hardest natural material, and has a Mohs hardness of 10. (from Mineral)
Image 22Contact twins, as seen in spinel (from Mineral)
Image 23Native gold. Rare specimen of stout crystals growing off of a central stalk, size 3.7 x 1.1 x 0.4 cm, from Venezuela. (from Mineral)
Image 24Perfect basal cleavage as seen in biotite (black), and good cleavage seen in the matrix (pink orthoclase). (from Mineral)
Image 25Black andradite, an end-member of the orthosilicate garnet group. (from Mineral)
Image 26When minerals react, the products will sometimes assume the shape of the reagent; the product mineral is termed a pseudomorph of (or after) the reagent. Illustrated here is a pseudomorph of kaolinite after orthoclase. Here, the pseudomorph preserved the Carlsbad twinning common in orthoclase. (from Mineral)
Image 27Pink cubic halite (NaCl; halide class) crystals on a nahcolite matrix (NaHCO₃; a carbonate, and mineral form of sodium bicarbonate, used as baking soda). (from Mineral)

Did you know ...?

... that the mineral shigaite (hexagonal crystal pictured) is named for the Japanese Prefecture where it was discovered in 1985?
... that naturally-occurring quasicrystals can be found in the rare minerals khatyrkite and cupalite?
... that the existence of the mineral frankdicksonite was predicted before its discovery?
... that seifertite, one of the densest polymorphs of silica, is named after Friedrich Seifert and has only been found in meteorites?

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v t e Minerals
Overview	Mineral Mineralogy History of mineralogy
Common minerals	Amphibole Bridgmanite K-feldspar Mica Olivine Plagioclase Pyroxene Quartz Spinel

v t e Phosphate minerals
Crystalline	Allanpringite Beraunite Brazilianite Eosphorite Fluorapatite Hydroxyapatite Lithiophilite Metatorbernite Monazite Struvite Taranakite Variscite Wavellite Xenotime
Cryptocrystalline	Turquoise Whitlockite
Amorphous	Santabarbaraite Scorodite

v t e Phyllosilicates
Micas	Aluminoceladonite Anandite Annite Aspidolite Balestraite Bityite Biotite Boromuscovite Bramallite Celadonite Chernykhite Chromphyllite Clintonite Eastonite Ephesite Ferroaluminoceladonite Ferroceladonite Fluorannite Fluorokinoshitalite Fluorophlogopite Fluorotetraferriphlogopite Garmite Glauconite Gorbunovite Hendricksite Illite Kinoshitalite Lepidolite Luanshiweiite Manganiceladonite Margarite Masutomilite Montdorite Muscovite Nanpingite Norrishite Orlovite Oxyphlogopite Paragonite Phlogopite Polylithionite Preiswerkite Roscoelite Siderophyllite Suhailite Tainiolite Tetraferriannite Trilithionite Voloshinite Wonesite Yangzhumingite
Talcs	Minnesotaite Talc Willemseite
Pyrophyllite series	Ferripyrophyllite Pyrophyllite
Kaolinites	Bismutoferrite Dickite Halloysite Hisingerite Kaolinite Nacrite
Serpentines	Amesite Antigorite Berthierine Brindleyite Caryopilite Chrysotile Cronstedtite Fraipontite Greenalite Guidottiite Kellyite Lizardite Manandonite Népouite Odinite Pecoraite
Corrensites	Aliettite Brinrobertsite Corrensite Dozyite Hydrobiotite Karpinskite Kulkeite Lunijianlaite Rectorite Saliotite Tosudite
Smectites and vermiculite family	Beidellite Ferrosaponite Montmorillonite Nontronite Saponite Sauconite Swinefordite Vermiculite Volkonskoite Yakhontovite
Chlorites	Baileychlore Borocookeite Chamosite Clinochlore Cookeite Donbassite Gonyerite Nimite Pennantite Sudoite
Allophanes	Allophane Chrysocolla Imogolite Neotocite
Sepiolites	Falcondoite Ferrisepiolite Sepiolite
Pyrosmalites	Friedelite Mcgillite Nelenite Pyrosmalite Schallerite
Stilpnomelanes	Bannisterite Franklinphilite Lennilenapeite Parsettensite Stilpnomelane
Structural groups mainly; based on rruff.info/ima, modified

v t e IMA–CNMNC / Nickel–Strunz IDs Mineral categories (classes, subclasses, divisions)
"Special cases" ("native elements and organic minerals")	"Native elements" (IDs 1) Organic minerals (IDs 10)
"Sulfides and oxides"	Sulfides (IDs 2.A–F) Sulfosalts; sulfarsenites, sulfantimonites, sulfbismuthites (IDs 2.G) Sulfosalts; sulfarsenates, sulfantimonates (IDs 2.K) Other sulfosalts (IDs 2.H–J and 2.L–M) Oxides (IDs 4.A–E, e.g. pyrochlore supergroup and corundum group) Hydroxides (IDs 4.F–G) Arsenates(IV), sulfates(IV) and iodates (IDs 4.J–K) Tellurium oxysalts Vanadium oxides (IDs 4.H)
"Evaporites and similars"	Carbonates (IDs 5.A–E) Nitrates (IDs 5.N) Borates (IDs 6) Halides (IDs 3)
"Mineral structures with tetrahedral units" (sulfate anion, phosphate anion, silicon, etc.)	Monomeric minerals (similar to nesosilicates) Sulfates(VI) (IDs 7.A–E) Thiosulphates (IDs 7.J) Chromates(VI) (IDs 7.F) Molybdates, wolframates, niobates(VI) (IDs 7.G–H) Phosphates(V) (IDs 8) Arsenates, vanadates(V) (IDs 8) Monomeric, isolated silicates (IDs 9.A) Germanates (IDs 9.J) Silicate frameworks, tectosilicates Zeolite frameworks, zeolite family (IDs 9.G) Other feldspathoids: nephelines (IDs 9.FA.05) Cancrinite-sodalite groups (IDs 9.FB.) Other tectosilicates (IDs 9.FA. and 9.FB.15, e.g. feldspars) Other silicate frameworks Cyclosilicates (IDs 9.C) Phyllosilicates (IDs 9.E, e.g. clays) Silica family (IDs 4.DA.) Inosilicates Single chain inosilicates (IDs 9.D, e.g. pyroxenes) Ribbon or multiple chain inosilicates (IDs 9.D, e.g. amphiboles) Other non monomeric minerals Unclassified silicates (IDs 9.H) Sorosilicates (IDs 9.B, e.g. epidote and seidozerite supergroups) Polymeric, isolated silicates (IDs 9.A, e.g. olivine and gadolinite supergroups) Other inorganic polymers (e.g. polyoxometalates; "polyphosphates", IDs 8.F)