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Chemistry Reference Libraries

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Aragonite
2005-05-26 12:17:18

Aragonite is 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...

Asbestos
2005-05-26 12:16:31

Asbestos (Greek a-, "not"; sbestos, "extinguishable") is a group of fibrous metamorphic minerals. The name is derived for its historical use in lamp wicks; the resistance of asbestos to fire has long been exploited for a variety of purposes. It was used in fabrics such as Egyptian burial cloths and Charlemagne's tablecloth, which, according to legend, he threw in a fire to clean. When...

Augite
2005-05-26 12:13:03

Augite is a mafic mineral described chemically as (Ca, Na)(Mg, Fe, Al)(Al, Si)2O6 or calcium sodium magnesium iron aluminium silicate. Structurally, it is a solid solution of the pyroxene group which also contains diopside and hedenbergite. The crystals are monoclinic and prismatic. It is found in igneous rocks such as gabbros and basalts, and in metamorphic rocks from hydrothermal vents....

Aurichalcite
2005-05-26 12:12:27

Aurichalcite is a mineral, usually found as a secondary mineral in copper and zinc deposits. Its chemical formula is (Zn,Cu)5(CO3)2(OH)6. The name probably originates from the Greek oreichalchos meaning "mountain copper".

Autunite
2005-05-26 12:11:56

Autonite (Hydrated Calcium Uranyl Phosphate) is a yellow - greenish fluorescent mineral with a Hardness of 2 - 2½. Due to the high content in uranium, it is radioactive and also used as uranium ore. If the mineral dries out, it converts to meta-autunite-I, which can turn into meta-autunite-II after heating. These two subsequent minerals are very rare in nature. For scientific studies it is...

Azurite
2005-05-26 12:11:19

Azurite is a carbonate mineral with chemical composition Cu3(CO3)2(OH)2, (copper carbonate hydroxide). Azurite is often found in association with the green mineral malachite as a result of the weathering and oxidation of copper sulfide minerals. The name azurite comes from the Arabic word for blue. Azurite is used in jewelry and also collected as a beautiful mineral specimen. Use as a...

Barite
2005-05-26 12:10:31

Barite (BaSO4) is a mineral consisting of barium sulfate. It is generally white or colorless, and is the main source of barium. Baryte is the British spelling. The radiating form is also sometimes refered to as Bologna Stone. Barite commonly occurs in lead-zinc veins in limestones, in hot spring deposits, and with hematite ore. It is often associated with the minerals anglesite and...

Bauxite
2005-05-26 12:09:54

Bauxite is a naturally occurring, heterogeneous material composed primarily of one or more aluminium hydroxide minerals, plus various mixtures of silica, iron oxide, titania, aluminosilicate, and other impurities in minor or trace amounts. The principal aluminium hydroxide minerals found in varying proportions with bauxites are gibbsite and the polymorphs boehmite and diaspore. Bauxites are...

Beryl
2005-05-26 12:08:48

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...

Beryllium
2005-05-26 12:07:27

Beryllium is the chemical element in the periodic table that has the symbol Be and atomic number 4. A toxic bivalent element, beryllium is a steel grey, strong, light-weight yet brittle, alkaline earth metal, that is primarily used as a hardening agent in alloys (most notably, beryllium copper). Notable characteristics Beryllium has one of the highest melting points of the light metals....

Word of the Day
tourtiere
  • a meat pie that is usually eaten at Christmas in Quebec
The word 'tourtiere' comes from the French tourte, or passenger pigeon.
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