Image: <bdi><a href="https://www.wikidata.org/wiki/Q56247090" class="extiw" title="d:Q56247090"><span title="mineral collector and dealer">Robert M. Lavinsky</span></a></bdi> (CC BY-SA 3.0)
orthorhombiccommonSulfates
Anhydrite
CaSO4
This specimen features blocky to prismatic crystals of pale blue to violet anhydrite, exhibiting a vitreous luster. The crystals show distinct cleavage planes.
Anhydrite Physical Properties
Mohs Hardness
3.5Crystal System
orthorhombicLuster
vitreousStreak Color
whiteCleavage
Perfect in three directions (pinacoidal), forming nearly cubic fragmentsFracture
unevenSpecific Gravity
2.95Colors
white, gray, pale blue, violet, pink, brownTransparency
transparentType Locality
St Gotthard basis tunnel (north section), NEAT Construction site, Amsteg, Reuss Valley, Uri, SwitzerlandMineral Group
SulfatesUses
industrial (source of sulfur, plaster, cement), soil conditioner, ornamental stone (as 'angelite')Associated Minerals
gypsum, halite, calcite, dolomite, sulfur, celestineRarity
commonGeological Context
Anhydrite commonly forms in evaporite deposits from the dehydration of gypsum in arid environments, or directly from the evaporation of seawater or saline lake water. It can also be found in hydrothermal veins.
