Image: <bdi><a href="https://www.wikidata.org/wiki/Q126871368" class="extiw" title="d:Q126871368"><span title="photographer from the United States">Darla Sondrol</span></a></bdi> (CC0)
monocliniccommonSulfates
Selenite
CaSO4•2H2O
Selenite is the clear, crystalline variety of gypsum, often forming well-developed, tabular to prismatic crystals, like these approximately 7 cm specimens.
Selenite Physical Properties
Mohs Hardness
2Crystal System
monoclinicLuster
vitreousStreak Color
whiteCleavage
Perfect on {010}, good on {100} and {111}Fracture
conchoidalSpecific Gravity
2.32Colors
colorless, whiteTransparency
transparentType Locality
Worldwide in evaporite deposits, including ChileMineral Group
SulfatesUses
collector, ornamental, source of gypsum for plaster and drywallAssociated Minerals
halite, anhydrite, calcite, dolomite, sulfurRarity
commonGeological Context
Selenite forms as an evaporite mineral, precipitating from saline waters in lagoons, playas, and caves as water evaporates. It is a common mineral in sedimentary environments.
