Gypsum
Image: Fredlyfish4 (CC BY-SA 3.0)
Mineral NameGypsum
Chemical FormulaCaSO₄·2H₂O
Mohs Hardness2
Crystal Systemmonoclinic
Lustervitreous
Streak Colorwhite
Cleavageperfect in one direction, good in two others
Fractureconchoidal
Specific Gravity2.32
Colorswhite, colorless, gray, yellow, pink, brown
Transparencytranslucent
Type LocalityCaprock Canyons State Park, Texas
Mineral GroupSulfates
Usesplaster of Paris, drywall, fertilizer, sculpture, collector
Associated Mineralshalite, anhydrite, clay minerals, shale, limestone
Raritycommon
Description
The image shows white, layered deposits of gypsum interbedded within reddish-brown sedimentary rock, exposed by erosion in a wash.
Geological Context
Gypsum commonly forms as an evaporite mineral in shallow marine basins or saline lakes, where the evaporation of water leads to the precipitation of sulfate minerals. These layers are often found within sedimentary sequences, indicating past arid conditions.
