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Anhydrite, Chihuahua, Mexico
CategorySulphate mineral
(repeatin unit)
Anhydrous calcium sulphate:CaSO4
Strunz clessification07.AD.30
Dana clessification28.3.2.1
Creestal seestemOrthorhombic – dipyramidal
Space groupOrthorhombic 2/m 2/m 2/m
Unit cella = 6.245(1) Å, b = 6.995(2) Å, c = 6.993(2) Å; Z = 4
ColourColourless tae fauch blae or violet gif transparent; white, mauve, rose, fauch broun or gray frae includit impurities
Creestal habitRare 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.
TwinninSimple or repeatitly on {011} common; contact twins rare on {120}
Cleavage[010] perfect
[100] perfect
[001] guid, resultin in pseudocubic fragments
Mohs scale haurdness3.5
SkinklePearly on {010}
vitreous tae glittie on {001}
vitreous on {100}
DiaphaneitySkyre tae leamin
Speceefic gravity2.97
Optical propertiesBiaxial (+)
Refractive indexnα = 1.567–1.574
nβ = 1.574–1.579
nγ = 1.609–1.618
Birefringenceδ = 0.042–0.044
PleochroismFor violet varieties
X = colourless tae fauch yellae or rose
Y = fauch violet or rose
Z = violet.
2V angle56–84°
Ither chairacteristicsSome specimens fluoresce; mony mair fluoresce efter heatin

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