Anhydrite

Real mineral · common · CaSO₄

Anhydrous calcium sulfate deposited in evaporite sequences. Absorbs water to convert to gypsum, expanding in volume. Found in association with halite and gypsum in marine evaporite deposits worldwide.

Identity

Formula

CaSO₄

Chemical class

sulfate

Also known as

Anhydrous gypsum

Crystallography

Crystal system

orthorhombic

Habits

massive, tabular, granular

Fracture

uneven

Physical properties

Mohs hardness

3.5

Density

2.98 g/cm³

Luster

vitreous, pearly

Colors

white, gray, blue, pink, violet

Streak

white

Transparency

transparent, translucent

Geology

Origins

sedimentary

Host rocks

evaporite, limestone

Associated minerals

Gypsum, Halite, Calcite, Sulfur

Geography

worldwide

Classification

Rarity

common

Gem quality

No

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