Gypsum is one of the more common minerals in sedimentary
environments. It is a major rock forming mineral that
produces massive beds, usually from precipitation out
of highly saline waters. Since it forms easily from
saline water, gypsum can have many inclusions of other
minerals and even trapped bubbles of air and water.
Gypsum has several variety names that are widely used
in the mineral trade. "Selenite" is the colorless
and transparent variety that shows a pearl like luster
and has been described as having a moon like glow. The
word selenite comes from the greek for Moon and means
Another variety is a compact fiberous aggregate called
"satin spar" . This variety has a very satin
like look that gives a play of light up and down the
A fine grained massive material is called "alabaster"
and is an ornamental stone used in fine carvings for
centuries, even eons.