mineral

Gypsum (Satin Spar/Desert Rose variety)

Calcium Sulfate Dihydrate (CaSO4·2H2O)

Hardness: 2 (Mohs scale); Color: White, pearly, or brownish-red due to inclusion of sand/clay; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Perfect in one direction; Specific gravity: 2.31-2.33

Hardness: 2 (Mohs scale)
Color: White, pearly, or brownish-red due to inclusion of sand/clay
Luster: Vitreous to pearly

Identified May 30, 2026More mineral →

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Physical properties

Formation & geological history

Formed in evaporitic environments where saline water evaporates in arid regions, leaving behind sulfate minerals. Often found in lake beds, playas, and desert soils where it crystallizes around sand grains.

Uses & applications

Used extensively in the manufacture of drywall (gypsum board), plaster of Paris, cement additive, and as a soil conditioner (land plaster) in agriculture. Distinctive specimens are prized by geological collectors.

Geological facts

Gypsum is one of the most common minerals in sedimentary environments. The variety shown involves significant sand inclusions, giving it a 'dirty' or earthy appearance often seen in desert environments.

Field identification & locations

Identified in the field by its extreme softness (can be scratched by a fingernail) and its distinctive tabular or fibrous habit. Commonly found in sedimentary basins and arid regions globally.

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