mineral

Satin Spar (Selenite)

Gypsum (Calcium Sulfate Dihydrate, CaSO4·2H2O)

Mohs hardness: 2 (can be scratched by a fingernail); Color: White to pearly; Luster: Silky or pearly; Crystal structure: Monoclinic with fibrous habit; Cleavage: Perfect in one direction; Specific gravity: approx 2.3.

Hardness: 2 (can be scratched by a fingernail)
Color: White to pearly
Luster: Silky or pearly

Identified June 27, 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 saline water or the hydration of anhydrite. Found in massive beds of sedimentary rock.

Uses & applications

Used commercially in plaster of paris, drywall, and as a soil conditioner. Fibrous varieties like this are popular in the metaphysical community and for decorative carving.

Geological facts

The name 'Selenite' comes from the Greek word 'selene' meaning moon, referring to its pale moonlight-like glow. The Naica Crystal Cave in Mexico contains world-record selenite crystals over 30 feet long.

Field identification & locations

Identified by its distinctive fibrous structure and extreme softness. It is very brittle and water-soluble over long periods. Commonly found in Morocco, Mexico, and the USA.

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

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

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

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral