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Mineral 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...

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....

Celestite
2005-05-26 11:56:59

Celestite (SrSO4) is a mineral consisting of strontium sulfate. The mineral is also known as celestine and is named for its occasional delicate blue color. Celestite occurs as crystals, and also in compact massive and fibrous forms. It is mostly found in sedimentary rocks, often associated with the minerals gypsum, anhydrite, and halite. The mineral is found worldwide, usually in small...

Colemanite
2005-05-26 11:13:48

Colemanite (Ca2B6O11·5H2O) is a borate mineral found in evaporite deposits. Colemanite is a secondary mineral that forms when borax is deposited, and then regularly covered with boron containing water. The boron remains after the water evaporates, and the boron and borax eventually form other minerals as for example Colemanite. It was named after William T. Coleman (1824-1893), owner of...

Galena
2005-05-26 10:59:49

Galena is a lead ore. This article describes Galena's mineral properties. In its chemically purified form, Galena is known as Lead Sulfide; refer to that article for chemical and industrial uses. Galena is one of the most abundant and widely distributed sulfide minerals, and is the most common ore of lead. Crystals are usually cubic, sometimes octahedral. It is often associated with the...

Garnierite
2005-05-26 10:59:02

Garnierite is a mineral composed of hydrous nickel silicates a member of the serpentine group with formula: (Ni,Mg)3Si2O5(OH). Népouite is a synonym. Garnierite is important as a source of nickel and is mined from laterite deposits which are formed by intense weathering and secondary enrichment of ultramafic igneous rocks.

Salt Halite
2005-05-26 10:40:24

Halite is the mineral of sodium chloride, NaCl, commonly known as rock salt. Halite forms isometric crystals. The mineral is colorless to white, light blue, dark blue, and pink. It commonly occurs with other evaporite deposit minerals such as several of the sulfates, halides and borates. Halite occurs in vast beds of sedimentary evaporite minerals that result from the drying up of enclosed...

Mica
2005-05-26 08:40:58

The mica group of minerals includes several closely related materials having highly perfect basal cleavage. All are monoclinic with a tendency towards pseudo-hexagonal crystals and are similar in chemical composition. The highly perfect cleavage, which is the most prominent characteristic of mica, is explained by the hexagonal sheet-like arrangement of its atoms. The word "mica" is thought...

Talc
2005-05-25 11:51:11

Talc is a mineral composed of hydrated magnesium silicate with the chemical formula H2Mg3(SiO3)4 or Mg3Si4O10(OH)2. It occurs as foliated to fibrous masses, its monoclinic crystals being so rare as to be almost unknown. It has a perfect basal cleavage, the folia non-elastic although slightly flexible. It is sectile and very soft, with a hardness of 1 (Talc is the softest known solid). It has a...

Word of the Day
baudekin
  • A rich embroidered or brocaded silk fabric woven originally with a warp of gold thread.
'Baudekin' seems to be an alternative form of 'baldachin,' from the Italian 'Baldacco,' Baghdad, the city where the material was made.
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