- Hydrous calcium sulfate, CaSO4 � 2H2O. A soft, common
rocks, where it sometimes occurs in thick beds interstratified with
limestones and shales.
Sometimes occurs as layer under bed of rock salt
since it is one of first minerals to crystallize
on evaporation of seawater. Alabaster is a
fine-grained massive variety of gypsum.
Source: Leet, L. Don. 1982.
Physical Geology, 6th Edition. Englewood Cliffs, NJ: Prentice-Hall
- A monoclinic mineral, 8[CaSO4 .2H2 O] ; colorless to white
in crystals, but massive beds may range from red to yellow to brown, gray,
or black; the most common natural sulfate; defines 2 on the Mohs hardness
scale; commonly associated with rock salt (halite) and anhydrite; forms
beds and lenses interstratified with limestone, shale, and clay, esp. in
rocks of Permian to Triassic age; also in volcanic fumarolic deposits; an
accessory mineral in metalliferous veins. Syn: gypsite
Dictionary of Mining, Mineral, and Related Terms