mineral

Selenite (Satin Spar Gypsum)

Calcium Sulfate Dihydrate (CaSO4·2H2O)

AI-generated identification · may be incorrect

Hardness: 2 on Mohs scale; Color: Colorless to white; Luster: Pearly to silky; Crystal Structure: Monoclinic; Cleavage: Perfect in one direction; Specific Gravity: 2.3

Hardness: 2 on Mohs scale
Color: Colorless to white
Luster: Pearly to silky

Identified April 26, 2026More mineral →

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Physical properties

Hardness: 2 on Mohs scale; Color: Colorless to white; Luster: Pearly to silky; Crystal Structure: Monoclinic; Cleavage: Perfect in one direction; Specific Gravity: 2.3

Formation & geological history

Formed as an evaporite mineral in sedimentary environments such as saline lakes and clay beds where sea water evaporates. Most deposits date from various periods of the Phanerozoic Eon.

Uses & applications

Used in the manufacture of plaster of Paris, wallboard (drywall), soil fertilizer, and widely popular as ornamental pieces and spiritual 'cleansing' crystals in the metaphysical community.

Geological facts

Selenite is named after the Greek word for Moon ('selene') due to its moon-like glow. The Naica Mine in Mexico contains giant selenite crystals measuring up to 39 feet long.

Field identification & locations

Identify by its extreme softness (can be scratched by a fingernail) and its fibrous, silky appearance. Commonly found in Morocco, Mexico, USA (Utah), and Brazil.