mineral

Satin Spar (often marketed as Selenite)

Gypsum (CaSO4·2H2O)

Hardness: 2 on Mohs scale (can be scratched by a fingernail). Color: White or colorless. Luster: Pearly to silky (satin-like). Crystal Structure: Monoclinic, typically fibrous. Cleavage: Perfect in one direction.

Hardness: 2 on Mohs scale (can be scratched by a fingernail)
Color: White or colorless
Luster: Pearly to silky (satin-like)

Identified July 18, 2026More mineral →

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Physical properties

Formation & geological history

Formed as an evaporite mineral in sedimentary environments, typically from the evaporation of seawater in ancient marine basins or in dry lake beds (playas).

Uses & applications

Used primarily for decorative carvings, metaphysical 'towers', and occasionally in the manufacture of plaster or drywall, though fibrous varieties are usually kept as specimens.

Geological facts

While commonly called 'Selenite' in the crystal trade, this fibrous white variety is technically 'Satin Spar.' True Selenite is transparent and platelike. It is one of the softest minerals on Earth and can dissolve if soaked in water for long periods.

Field identification & locations

Identify in the field by its extreme softness and silky, fibrous appearance. It is commonly found in Morocco, Mexico (Naica Mine), and the USA (Utah). Use a fingernail to test for hardness.

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Sandstone with Mineral Veining or Crust

Sedimentary Sandstone (mostly SiO2 with Fe2O3 tinting)

sedimentary

Schist

Metamorphic

Potassium Feldspar (Orthoclase)

Orthoclase (KAlSi3O8)

mineral

Gypsum (variety Selenite or Alabaster)

Calcium sulfate dihydrate (CaSO4·2H2O)

Mineral

Nephrite Jade

Nephrite

Mineral/Rock