An important construction material that has been used for thousands of years
Article by: Hobart M. King, Ph.D., RPG
What is Gypsum?
Gypsum is an evaporite mineral most commonly found in layered sedimentary deposits in association with halite, anhydrite, sulfur, calcite, and dolomite. Gypsum (CaSO4.2H2O) is very similar to Anhydrite (CaSO4). The chemical difference is that gypsum contains two waters and anhydrite is without water. Gypsum is the most common sulfate mineral.
Uses of Gypsum
Gypsum uses include: manufacture of wallboard, cement, plaster of Paris, soil conditioning, a hardening retarder in portland cement. Varieties of gypsum known as "satin spar" and "alabaster" are used for a variety of ornamental purposes; however, their low hardness limits their durability.
Physical Properties of Gypsum
|Color||Clear, colorless, white, gray, yellow, red, brown|
|Luster||Vitreous, silky, sugary|
|Diaphaneity||Transparent to translucent|
|Diagnostic Properties||Cleavage, specific gravity, low hardness|
|Chemical Composition||Hydrous calcium sulfate, CaSO4.2H2O|
|Uses||Used to manufacture dry wall, plaster, joint compound. An agricultural soil treatment.|
|Rock, Mineral and Fossil Collections.|
|Mineral Identification Chart|
|Abandoned Mine Accidents|