Mineral Species: Gypsum 

Chemical Formula: CaSO4.2H20

Chemical Name: Hydrous Calcium Sulfate

Mineral Class: Sulfate

Mineral Notes: Gypsum is the commonest sulfate and is a frequent component of sedimentary rocks, particularly marine salt deposits. The Satin Spar variety is a form in which the crystals adopt a fibrous habit. They usually develop in small veins and the fibers grow at right angles to the vein walls so the length of the fibers can only be as long as the vein is wide. 

Description: A doubly terminated floater crystal of Gypsum. The interior shows growth zones in the middle but the terminations are very clear and gemmy. A very attractive display specimen.