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)
monocliniccommonSulfates
Gypsum
CaSO₄·2H₂O
A small, well-formed ball of twinned Selenite crystals, featuring a prominent, super-gemmy 1.6 cm twinned crystal growing from the main mass. The exceptional clarity and color of this specimen are noted as unusual.
Gypsum Physical Properties
Mohs Hardness
2Crystal System
monoclinicLuster
vitreousStreak Color
whiteCleavage
Perfect on {010}, good on {100}, distinct on {111}Fracture
conchoidalSpecific Gravity
2.32Colors
colorless, white, gray, yellow, brown, pinkTransparency
transparentType Locality
Block and Brady One Pit, Red River Floodway, near Winnipeg, Manitoba, CanadaMineral Group
SulfatesUses
plaster, drywall, fertilizer, cement, sculpture, collectorAssociated Minerals
halite, anhydrite, calcite, dolomite, sulfurRarity
commonGeological Context
Gypsum forms primarily as an evaporite mineral in shallow marine basins or saline lakes, often in association with other evaporite minerals like halite and anhydrite. It can also form from the hydration of anhydrite in sedimentary environments.
