انیدریت

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 deve

Key facts

Mineral.name: Anhydrite
Mineral.category: Sulfate mineral
Mineral.boxbgcolor: b7dfda
Mineral.image: Anhydrite_HMNH1.jpg
Mineral.imagesize: 260px
Mineral.caption: Anhydrite, from Chihuahua, Mexico
Mineral.formula: CaSO4
Mineral.IMAsymbol: Anh
Mineral.strunz: 7.AD.30
Mineral.dana: 28.3.2.1
Mineral.system: Orthorhombic
Mineral.class: Dipyramidal (mmm) H–M symbol: ( )
Mineral.symmetry: Amma
Mineral.unit cell: a = 6.245(1) Å, b = 6.995(2) Åc = 6.993(2) Å; Z = 4
Mineral.color: Colorless to pale blue or violet if transparent; white, mauve, rose, pale brown or gray from included impurities
Mineral.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
Mineral.twinning: Simple or repeatedly on {011} common; contact twins rare on {120}
Mineral.cleavage: [010] perfect [100] perfect [001] good, resulting in pseudocubic fragments