How does gypsum occur in nature?

Question

Does it occur as gypsum in the ground or is it found in rocks? If so what rocks is it commonly found?

Answer 1

Gypsum is commonly found in shales, and is a result of the reduction (redox reactions) of sulfur, such as that in pyrite (FeS2). Gypsum also forms as an evaporite in ephemeral arid.lakes, and as a mineral is called selenite. Both of these are sedimentary environments, the former being siliclastic and the latter being chemical precipitation.

Answer 2

Gypsum occurs in nature as flattened and often twinned crystals and transparent cleavable masses called selenite. It may also occur silky and fibrous, in which case it is commonly called satin spar. Finally it may also be granular or quite compact. In hand-sized samples, it can be anywhere from transparent to opaque. A very fine-grained white or lightly-tinted variety of gypsum is called alabaster, which is prized for ornamental work of various sorts. In arid areas, gypsum can occur in a flower-like form typically opaque with embedded sand grains called desert rose.