Collection: Anhydrite

Anhydrite is an anhydrous calcium sulfate,

Crystal system- Orthorhombic
Mineral class- Sulfate
Crystal habits- Tabular or prismstic crystals are rare. It typically occurs as massive,granular, nodules or fibrous cleavage masses with three directions of tight-angle cleavage.
Hardness- 3.3.5 on the MOHs scale
Rock formation:
Environment- Sedimentary evaporite deposits formed by the direct precipitation of calcium sulfate from evaporating seawater in arid regions,or via the deep subsurface dehydration of gypsum.
Transformation- readily absorbs water to transform back into gypsum,which causes a significant volume expansion of up to 60%