Mineral - Anhydrite
Anhydrite
Chemical Properties
Mineral Class
Sulphates
Toxicity
none
Formula
Ca[SO₄]
Unit Cell
a=6.99 b=7.00 c=6.25 Z=4
Physical Properties
Hardness
3 - 3.5
Streak
white
Density
Normal (2-3,5)
Cleavage
Perfect after {010}, good after {100}, imperfect after {001}
Fracture
splintery,
uneven
Tenacity
Brittle
Optical Properties
Color
whitebluepink
Birefringence
0.044
Luster
Vitreous,
Greasy,
Pearly
Transparency
translucent,
transparent
Pleochroism
X: Farblos-Gelb-Rosa
Y: Rosa-Violett
Z: Violett
Geomineralogical Properties
Crystal System
orthorhombic
Point Group
orthorhombic-dipyramidal - 2/m 2/m 2/m
Space Group
Cmcm (63)
Habit
blocky, coarse, massive, prismatic, tabular
Formation
Evaporite, due to dehydration of gypsum; volcanic in fumaroles; secondary in hydrothermal veins
Paragenesis
Twinning
Contact twins after {120}
Rarity
Common
Synonyms
Anhydrite
Composition
Elements
Mass
SO₃
58.37
CO₂
0.17
(Al,Fe)₂O₃
0.06
CaO
41.13
FeS₂
0.02
Japan (Palache et al. 1952)
Name and first discovery : Named in 1804 by Abraham Gottlob Werner from the Greek word "anhydros", meaning "without water", in reference to the absence of water in its composition, unlike gypsum, which contains water.
Chemistry :
Synonyms : Karstenite, Muriacite
Varieties : Angelite, Vulpinite
Abbreviation : Anh
literature
Palache, C., Berman, H., & Frondel, C. (1952). Dana's system of mineralogy. Geologiska Föreningen i Stockholm Förhandlingar , 74 (2), 218-219.