Anhydrite

| Mineral List | Rock List | Guidelines for Rock Collections |

Mineral class: Sulfate
Composition: Calcium sulfate, CaSO₄
Hardness: 3 - 3.5
Luster: Pearly to vitreous
Color: Light grey, white, blue-grey
Streak: White
Cleavage: Perfect, 3 planes at 90 degrees. No cleavage if massive.
Crystal form: May be fibrous
Environment: Evaporite deposit (like gypsum and halite).
Comments:
Scratched by knife but not penny or fingernail.

Crystals rare, usually massive (with no cleavage), associated with gypsum.

Differs from gypsum in being unhydrated.

Weathers to gypsum at surface exposures.
[anhydrite.jpg]

Mineral class:	Sulfate
Composition:	Calcium sulfate, CaSO₄
Hardness:	3 - 3.5
Luster:	Pearly to vitreous
Color:	Light grey, white, blue-grey
Streak:	White
Cleavage:	Perfect, 3 planes at 90 degrees. No cleavage if massive.
Crystal form:	May be fibrous
Environment:	Evaporite deposit (like gypsum and halite).
Comments:	Scratched by knife but not penny or fingernail. Crystals rare, usually massive (with no cleavage), associated with gypsum. Differs from gypsum in being unhydrated. Weathers to gypsum at surface exposures.