mineral

Selenite (Giant Crystals)

Selenite (CaSO4·2H2O)

AI-generated identification · may be incorrect

Hardness: 2 (Mohs scale), Color: Colorless to white/pearly, Luster: Vitreous to pearly, Crystal structure: Monoclinic, Cleavage: Perfect, Specific Gravity: 2.3

Identified January 8, 2026More mineral →

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Physical properties

Hardness: 2 (Mohs scale), Color: Colorless to white/pearly, Luster: Vitreous to pearly, Crystal structure: Monoclinic, Cleavage: Perfect, Specific Gravity: 2.3

Formation & geological history

Formed by hydrothermal fluids saturated with calcium sulfate slowly cooling over 500,000 years in stable temperatures (around 58 degrees Celsius).

Uses & applications

Used in plaster of Paris, wallboard, cement, soil conditioner/fertilizer, and as ornamental healing crystals.

Geological facts

The image shows the Cave of the Crystals in Naica, Mexico, home to the largest selenite crystals ever found, some reaching 12 meters in length and weighing 55 tons.

Field identification & locations

Identify by its softness (can be scratched with a fingernail) and crystalline transparency. Commonly found in Chihuahua (Mexico), Morocco, and the USA (Utah).

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