"Angelite" redirects here. For the musical ensemble, see Angelite (choir).
Not to be confused with anhydride.
Anhydrite
Anhydrite, from Chihuahua, Mexico
General
Category
Sulfate mineral
Formula (repeating unit)
CaSO4
IMA symbol
Anh[1]
Strunz classification
7.AD.30
Dana classification
28.3.2.1
Crystal system
Orthorhombic
Crystal class
Dipyramidal (mmm) H–M symbol: (2/m2/m2/m)
Space group
Amma
Unit cell
a = 6.245(1) Å, b = 6.995(2) Å c = 6.993(2) Å; Z = 4
Identification
Color
Colorless to pale blue or violet if transparent; white, mauve, rose, pale brown or gray from included impurities
Crystal habit
Rare tabular and prismatic crystals. Usually occurs as fibrous, parallel veins that break off into cleavage fragments. Also occurs as grainy, massive, or nodular masses
Twinning
Simple or repeatedly on {011} common; contact twins rare on {120}
Cleavage
[010] perfect [100] perfect [001] good, resulting in pseudocubic fragments
Fracture
Conchoidal
Tenacity
Brittle
Mohs scale hardness
3.5
Luster
Pearly on {010} vitreous to greasy on {001} vitreous on {100}
For violet varieties X = colorless to pale yellow or rose Y = pale violet or rose Z = violet.
2V angle
56–84°
Fusibility
2
Other characteristics
Some specimens fluoresce; many more fluoresce after heating
References
[2][3][4][5]
Anhydrite, or anhydrous calcium sulfate, is a mineral with the chemical formula CaSO4. It is in the orthorhombic crystal system, with three directions of perfect cleavage parallel to the three planes of symmetry. It is not isomorphous with the orthorhombic barium (baryte) and strontium (celestine) sulfates, as might be expected from the chemical formulas. Distinctly developed crystals are somewhat rare, the mineral usually presenting the form of cleavage masses. The Mohs hardness is 3.5, and the specific gravity is 2.9. The color is white, sometimes greyish, bluish, or purple. On the best developed of the three cleavages, the lustre is pearly; on other surfaces it is glassy. When exposed to water, anhydrite readily transforms to the more commonly occurring gypsum, (CaSO4·2H2O) by the absorption of water. This transformation is reversible, with gypsum or calcium sulfate hemihydrate forming anhydrite by heating to around 200 °C (400 °F) under normal atmospheric conditions.[6] Anhydrite is commonly associated with calcite, halite, and sulfides such as galena, chalcopyrite, molybdenite, and pyrite in vein deposits.
Anhydrite, or anhydrous calcium sulfate, is a mineral with the chemical formula CaSO4. It is in the orthorhombic crystal system, with three directions...
compound with the formula CaSO4 and related hydrates. In the form of γ-anhydrite (the anhydrous form), it is used as a desiccant. One particular hydrate...
Acetic anhydride, or ethanoic anhydride, is the chemical compound with the formula (CH3CO)2O. Commonly abbreviated Ac2O, it is the simplest isolable anhydride...
(350 °F), the nearly water-free form, called γ-anhydrite (CaSO4·nH2O where n = 0 to 0.05) is produced. γ-anhydrite reacts slowly with water to return to the...
evaporites. The most common marine evaporites are calcite, gypsum and anhydrite, halite, sylvite, carnallite, langbeinite, polyhalite, and kainite. Kieserite...
baryte, celestine (strontium sulfate), anglesite (lead sulfate), and anhydrite (calcium sulfate). Baryte and celestine form a solid solution (Ba,Sr)SO4...
found in limestone and the fossilised remnants of early sea life; gypsum, anhydrite, fluorite, and apatite are also sources of calcium. The name derives from...
precipitated as anhydrite (CaSO4). When the overall temperature of the cave started to drop below 56 °C (133 °F), the hydrothermal and sedimentary anhydrite crystals...
government from 2021. In 1983, NIREX announced a proposal to use the disused anhydrite mine as a site for the disposal of intermediate level nuclear waste. There...
fresh water ponds and salt lakes. There are several variable beds of anhydrite and gypsum and the central body of most of the formation is a massive...
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...
The halite (salt) is removed first, leaving behind gypsum and anhydrite. The anhydrite and gypsum react with organic material to form calcite. The classic...
formed crystals and dispersed grains often embedded within gypsum and anhydrite crystals. It has a Mohs hardness of 7 to 7.5 and a specific gravity of...
Formation is composed chiefly of dolomite and shale, interbedded with anhydrite, gypsum, and salt. Stratigraphically, the Salina is placed in the Late...
The drilling perforated an anhydrite layer and caused high-pressure groundwater to come into contact with the anhydrite, which then began to expand....
The hydration of anhydrite to form gypsum, for example, results in an increase of volume by 63%. In arid environments where anhydrite is widespread, a...
blanketed by the widespread deposition of Louann Salt and associated anhydrite evaporites. During the late Jurassic, continued rifting widened the basin...
consists of dolomite with interbedded anhydrite and gypsum, with the upper part being limestone, with dolomite and anhydrite in part. The thickness of the Lower...
that the drilling perforated an anhydrite layer bringing high-pressure groundwater to come into contact with the anhydrite, which then began to expand. Currently...
materials such as plaster and drywall. The anhydrous equivalent of gypsum is anhydrite; it can form directly from seawater in highly arid conditions. The barite...
project that concerns exploitation of Pagiriai anhydrite deposit. The project includes mining of anhydrite, a mine with underground warehouses, building...
carbonate rocks (dolomite and limestone) and evaporitic rocks (halite, anhydrite and potash), with lesser amounts of dolomitic mudstone and shale. Some...
initial stages of a vent chimney begin with the deposition of the mineral anhydrite. Sulfides of copper, iron, and zinc then precipitate in the chimney gaps...
Breisgau, Germany, tectonic uplift occurred instead. A previously isolated anhydrite layer came in contact with water and turned it into gypsum, doubling its...
Global Information