Plagioclase feldspars are a very important group of igneous rock forming tectosilicate minerals. Plagioclase comprises a solid solution series: NaAlSi3O8 (Albite)- CaAl2Si2O8 (Anorthite) Plagioclase feldspars range between two endmembers: the sodic feldspar endmember albite and the calcic feldspar endmember anorthite. The composition of plagioclase feldspar is typically determined by the percentage of anorthite (%An) in system. The members of this series are known as ...

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Ruby is a red gemstone, a variety of the mineral corundum (aluminium oxide) in which the color is caused mainly by chromium. Its name originates from ruber, Latin for red. Natural rubies are exceptionally rare, though artificial ones (sometimes called created ruby) can be manufactured which are comparatively inexpensive. Rubies are mined in Africa, Asia, Australia and Greenland. They are most often found in Myanmar, Sri Lanka and Thailand, though they have also been found in Montana and South Carolina. Sometimes s ...

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Aquamarine (Lat. aqua marina, "water of the sea") is a gemstone-quality transparent variety of beryl, having a delicate blue or bluish-green colour, suggestive of the tint of sea-water. It's closely related to the emerald. It occurs at most localities which yield ordinary beryl, some of the finest coming from Russia. The gem-gravels of Sri Lanka contain aquamarine. Clear yellow beryl, such as occurs in Brazil, is sometimes called aquamarine chrysolite. When corundum presents the bluish tint of typical aq ...

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This article is about minerals in the geologic sense; for nutrient minerals see dietary mineral; for the band see Mineral (band). Minerals are natural compounds formed through geological processes. The term "mineral" encompasses not only the material's chemical composition but also the mineral structures. Minerals range in composition from pure elements and simple salts to very complex silicates with thousands of known forms (organic compounds are usually excluded). The study of minerals is called mineralogy. < ...

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• Mineral - Mineral definition and classification
• Mineral - Minerals and rocks
• Mineral - Physical properties of minerals
• Mineral - Chemical properties of minerals

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A gemstone is a mineral, rock (as in lapis lazuli) or petrified material that when cut or faceted and polished is collectible or can be used in jewellery. Others are organic, such as amber (fossilised tree resin) and jet (a form of coal). Some beautiful gemstones are too soft or too fragile to be used in jewelry, for example, single-crystal rhodochrosite, but are exhibited in museums and are sought by collectors. Gemstone - Characteristics and classification. Gemstones are described by gemologists using tec ...

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• Gemstone - Characteristics and classification
• Gemstone - Value
• Gemstone - Factors Influencing Esteem
• Gemstone - Synthetic and artificial gemstones
• Gemstone - Gemstone list

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Zircon is a mineral belonging to the group of nesosilicates. Its chemical formula is ZrSiO4. Hafnium is almost always present ranging from 1 to 4%. The crystal structure of zircon is tetragonal crystal class. The natural color of zircon varies between colorless, yellow-golden, red, brown or green. Colorless specimens that show gem quality are a popular substitute for diamond; these specimens are also know ...

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• Zircon - Properties
• Zircon - Uses
• Zircon - Zircons and the age of Earth

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Zoisite is a calcium aluminium hydroxy sorosilicate belonging to the epidote group of minerals. Zoisite is named after Austrian scientist Baron Sigmund Zois von Edelstein (Baron von Zois), whom discovered the mineral in the Sau-Alp mountains of Austria in 1805. Zoisite was first known as saualpite, after its type locality. Transparent material is fashioned into gemstones while translucent-to-opaque mat ...

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Uraninite is a uranium-rich mineral with a composition that is largely UO2 (uranium oxide), but which also contains UO3 and oxides of lead, thorium, and rare earths. It is most commonly known in the variety pitchblende. All uraninite minerals contain a small amount of radium as a radioactive decay product of uranium; it was in pitchblende from the Jáchymov in Czechoslovakia that Marie Curie discovered radium. Uraninite also always contains small amounts of the lead isotopes, Pb-206 and Pb-207, the end pro ...

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• Uraninite - Reference

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An alluvial deposit is an accumulation of alluvium (sediment), sometimes containing valuable ore and gemstones, or simply consisting of gravel, sand, or clay, in the bed or former bed of a river. Valuable materials such as gold may be extracted using techniques of placer mining. Historically, gemstones (diamonds in particular), were found in the gravels of India. They continue to be mined from alluvium in Myanmar and Sri L ...

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In geography, a desert is a landscape form or region that receives little precipitation - less than 250 mm per year. Deserts have a reputation for supporting very little life. Compared to wetter regions this may be true, although upon closer examination, deserts often harbor a wealth of life that usually remains hidden (especially during the daylight) to preserve moisture. Approximately one-third of Earth's land surface is desert. (See a map of the world's non-polar deserts, http: ...

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• Desert - Types of desert
• Desert - Montane deserts
• Desert - Desert features
• Desert - Soils
• Desert - Vegetation
• Desert - Water
• Desert - Mineral resources
• Desert - List of deserts
• Desert - Americas
• Desert - Africa
• Desert - Asia-Pacific

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Sodalite is a rare, rich royal blue mineral widely enjoyed as an ornamental stone. Although massive sodalite samples are opaque, crystals are usually transparent to translucent. Sodalite is a member of the sodalite group and together with hauyne, nosean and lazurite is a common constituent of lapis lazuli. Discovered in 1806 in Greenland, sodalite did not become important as an ornamental stone until 1891 when vast deposits of fine material were discovered in Ontario, Canada. It has since been named Princess Blue after P ...

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• Sodalite - Properties
• Sodalite - Occurrence

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Cinnabar (German Zinnober), sometimes written cinnabarite, is a name applied to red mercury(II) sulfide (HgS), or native vermilion, the common ore of mercury. The name comes from the Greek, used by Theophrastus, and was probably applied to several distinct substances. Other sources say the word comes from the Persian zinjifrah, originally meaning "lost". Cinnabar was mined by the Roman Empire for its mercury content and it has been the main ore of mercury throughout the centuries. Some mines used by the Rom ...

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• Cinnabar - Of note

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The miners' strike of 1984-5 was a major piece of industrial action affecting the British coal industry. It was a defining event in the history of industrial relations in the UK. UK miners' strike 1984-1985 - History. In 1984, the National Coal Board (the UK Public Body which controlled coal mining) announced that an agreement reached after the 1974 miners' strike had become obsolete, and that they intended to close 20 coal mines because they were uneconomical. 20,000 jobs would be lost, and many communitie ...

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• UK miners' strike 1984-1985 - History
• UK miners' strike 1984-1985 - After the strike
• UK miners' strike 1984-1985 - Strike in artistic depictions
• UK miners' strike 1984-1985 - Books

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The carbonate mineral calcite is a calcium carbonate corresponding to the formula CaCO3 and is one of the most widely distributed minerals on the Earth's surface. It is a common constituent of sedimentary rocks, limestone in particular. It is also the primary mineral in metamorphic marble. It also occurs as a vein mineral in deposits from hot springs, and also occurs in caverns as stalactites and stalagmites. Calcite is often the primary constituent of the shells of marine organisms (e.g. plankton, bivalves, etc.). Calcite represents the stable form of calcium carbonat ...

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• Calcite - Properties
• Calcite - External link

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Emerald (Be3Al2SiO6) is a variety of the mineral beryl, colored green by trace amounts of chromium and sometimes iron. It is highly prized as a gemstone and by weight is the most valuable gemstone in the world, often made more so by inclusions, which all emeralds have. Beryl has a hardness of 8 on the 10 point Mohs scale of hardness. Emerald - Synthetic emerald. Emerald is a rare and valuable gemstone and, as such, provided the incentive for developing synthetic emeralds. Bo ...

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• Emerald - Synthetic emerald
• Emerald - Culture and folklore

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Jasper is an opaque, impure variety of quartz that is usually red, yellow or brown in color. This mineral breaks with a smooth surface, and is often used for ornamentation or as a gemstone. It can be highly polished and is used for vases, seals, and at one time for snuff boxes. When the colors are in stripes or bands, it is called striped or banded jasper. Jaspilite is a banded iron formation rock that often has distinctive bands of jasper. The ...

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• Jasper - Etymology
• Jasper - Types of Jasper

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Aragonite is a carbonate mineral, a polymorph of the mineral calcite, both having the chemical composition CaCO3. Its structure differs from calcite and leads to a different crystal shape, an orthorhombic system with acicular crystals. By repeated twinning pseudo-hexagonal forms result. It may be columnar or fibrous, occasionally in branching stalactitic forms called flos-ferri (flowers of iron) from their association with the ores at the Carthinian iron mines. The type location for aragonite is Molina de Aragón (Guadalaja ...

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• Aragonite - External link

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Hematite (AE) or haematite (BE) is the mineral form of Iron (III) oxide, (Fe2O3), one of several iron oxides. The ore sometimes contains slight amounts of titanium. When shaped into ornaments, it is often called black diamond. Hematite is a very common mineral, coloured black to steel or silver-gray, brown to reddish brown, or red. It is mined as the main ore of iron. Varieties include Bloodstone, Iron Rose, Kidney Ore, Martite, Paint Ore, Specularite (Specular Hematite), Rainbow Hematite and Titano-hematite. While the forms of hematite vary, they all have a rust-red streak. Hematite i ...

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• Hematite - Hematite on Mars

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The mineral beryl is a beryllium aluminium cyclosilicate with the chemical formula Be3Al2(SiO3)6. The hexagonal crystals of beryl may be very small or range to several meters in size. Terminated crystals are relatively rare. Beryl exhibits conchoidal fracture, has a hardness of 7.5-8, a specific gravity of 2.63-2.80. It has a vitreous lustre and can be transparent or translucent. Its cleavage is poor basal and its habit is dihexagonal bipyramidal. Pure beryl is colorless, but it is frequentl ...

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• Beryl - Varieties
• Beryl - Deposits
• Beryl - Applications

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For the logical fallacy, see Amphibology. Amphibole defines an important group of dark-colored rock-forming inosilicate minerals composed of double chain SiO4 tetrahedra linked at the vertices and generally containing ions of iron and/ or magnesium in their structures. In chemical composition and general characteristics they are very similar to the pyroxenes and, like them, fall into three series according to their system of crystallization. The chief difference between amphiboles and pyroxenes is in cleavage: ...

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• Amphibole - Amphibole groups
• Amphibole - Reference

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SI units were used where possible. Unless otherwise stated, standard conditions were used. Disclaimer and references Sodium bicarbonate (NaHCO3), or sodium hydrogen carbonate, also known as baking soda and bicarbonate of soda, is a soluble white anhydrous or crystalline chemical compound, with a slight alkaline taste resembling that of sodium carbonate. It is foun ...

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• Sodium bicarbonate - Safety

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