mineral

Selenite (variety of Gypsum)

Calcium sulfate dihydrate (CaSO4·2H2O)

Hardness: 2 on Mohs scale (can be scratched by a fingernail). Color: Colorless to white. Luster: Vitreous to pearly/silky. Crystal structure: Monoclinic with fibrous or bladed habit. Cleavage: Perfect in one direction.

Hardness: 2 on Mohs scale (can be scratched by a fingernail)
Color: Colorless to white
Luster: Vitreous to pearly/silky

Identified June 28, 2026More mineral →

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Physical properties

Formation & geological history

Formed as an evaporite mineral in sedimentary environments, often resulting from the evaporation of seawater or from the alteration of other minerals in hydrothermal veins.

Uses & applications

Used in the manufacturing of plaster of Paris, wallboard (drywall), and as a soil amendment. Translucent varieties are used in decorative carvings and metaphysical specimen collecting.

Geological facts

The name Selenite comes from the Greek word 'selene', meaning moon, due to its soft pearly luster. Some of the world's largest crystals are selenite, found in the Cave of the Crystals in Naica, Mexico.

Field identification & locations

Identify in the field by its extreme softness (scratchable with a thumbnail) and its fibrous, satiny texture. Commonly found in desert regions and sedimentary basins.

Other mineral specimens

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Gypsum (variety Selenite or Alabaster)

Calcium sulfate dihydrate (CaSO4·2H2O)

Mineral

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock