Anhydrite

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Anhydrite
Anhydrite HMNH1.jpg
Anhydrite, Chihuahua, Mexico
General
Category Sulphate mineral
Formula
(repeating unit)
Anhydrous calcium sulphate:CaSO4
Strunz classification 07.AD.30
Dana classification 28.3.2.1
Crystal symmetry Orthorhombic 2/m 2/m 2/m
Unit cell a = 6.245(1) Å, b = 6.995(2) Å, c = 6.993(2) Å; Z = 4
Identification
Color Colourless tae fauch blae or violet gif transparent; white, mauve, rose, fauch broun or gray frae includit impurities
Crystal habit Rare tabular an prismatic crystals. Uisually occurs as fibrous, parallel veins that break aff intae cleavage fragments. Occurs as grainy, massive, or nodular masses an aw.
Crystal seestem Orthorhombic – dipyramidal
Twinnin Simple or repeatitly on {011} common; contact twins rare on {120}
Cleavage [010] perfect
[100] perfect
[001] guid, resultin in pseudocubic fragments
Fractur Conchoidal
Tenacity Brickle
Mohs scale hairdness 3.5
Luster Pearly on {010}
vitreous tae glittie on {001}
vitreous on {100}
Streak White
Diaphaneity Skyre tae leamin
Specific gravity 2.97
Optical properties Biaxial (+)
Refractive index nα = 1.567–1.574
nβ = 1.574–1.579
nγ = 1.609–1.618
Birefringence δ = 0.042–0.044
Pleochroism For violet varieties
X = colourless tae fauch yellae or rose
Y = fauch violet or rose
Z = violet.
2V angle 56–84°
Fusibility 2
Ither characteristics Some specimens fluoresce; mony mair fluoresce efter heatin
References [1][2][3][4]

Anhydrite is a mineral—anhydrous calcium sulphate, CaSO4.

References[eedit | eedit soorce]

  1. Klein, Cornelis and Cornelius S. Hurlbut, 1985, Manual of Mineralogy, 20th ed., John Wiley and Sons, New York, ISBN 0-471-80580-7
  2. Anhydrite. Webmineral
  3. Anhydrite. Mindat.org
  4. Handbook of Mineralogy