mineral

Satin Spar Selenite

Fibrous Gypsum (CaSO4·2H2O)

Hardness: 2 (soft enough to scratch with a fingernail); Color: Pearly white to translucent; Luster: Silky/Satin; Crystal Structure: Monoclinic; Specific Gravity: 2.3; Cleavage: Perfect in one direction

Hardness: 2 (soft enough to scratch with a fingernail)
Color: Pearly white to translucent
Luster: Silky/Satin

Identified July 14, 2026More mineral →

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Physical properties

Formation & geological history

Formed as an evaporite mineral in sedimentary environments such as saline lakes and clay beds where sea water or mineral-rich groundwater evaporates. It can range in age from millions of years old to relatively modern formations.

Uses & applications

Largely used in the metaphysical and wellness community for 'cleansing' other stones. Industrially, gypsum is used in plaster of Paris, drywall, and as a soil conditioner.

Geological facts

While commonly called Selenite in the crystal market, this specific fibrous variety is technically Satin Spar. True Selenite is transparent and platy. It is one of the softest minerals on Earth and is water-soluble over long periods of time.

Field identification & locations

Identified by its signature silky sheen and long fibrous structure. In the field, look in evaporite basins. It is extremely soft and can be easily scratched by a fingernail, which helps distinguish it from similar-looking quartz or calcite.