mineral

Selenite gypsum crystal

Gypsum (CaSO₄·2H₂O), fibrous/selenite variety

AI-generated identification · may be incorrect

Colorless to white, transparent to translucent, vitreous to pearly luster, commonly bladed or fibrous with perfect {010} cleavage; Mohs hardness 2, specific gravity about 2.3. The specimen appears to be a slender, polished or naturally elongated blade.

Identified September 14, 2026More mineral →

Explore Selenite gypsum crystal in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Forms by evaporation of sulfate-rich water in sedimentary evaporite basins, saline lakes, caves, and hot-spring environments; deposits range from recent to Paleozoic and younger geological ages.

Uses & applications

Used to manufacture plaster, drywall, cement additives, and soil conditioners; clear crystals are popular inexpensive mineral specimens and may be used decoratively, though they are too soft for durable jewelry.

Geological facts

Selenite is not a separate mineral species but a transparent variety of gypsum. It can be scratched easily with a fingernail and dissolves slowly in water.

Field identification & locations

Identify by its very low hardness, light weight, perfect cleavage, and ability to split into thin sheets; common localities include Mexico, Spain, Morocco, the United States, and Australia. Avoid water, abrasion, and heat when collecting or displaying it.