Rock Gypsum
(c) 2008 Andrew Alden, licensed to About.com, Inc. (fair use policy)
Rock gypsum is the name for a stone composed of the mineral gypsum. Rock gypsum can be earthy or, as in this specimen, coarsely crystalline. It forms where shallow sea basins or salt lakes become restricted and begin to dry out, until crystals of gypsum come out of solution. It is therefore an evaporite, as is rock salt. This specimen came from southern Nevada, where large deposits of rock gypsum are mined and processed into wallboard and other industrial products.
Fossils
Geologic Features and Processes
Glaciers and Ice
Landforms
Minerals
Rocks
Geology and Society
