mineral

Orange Satin Spar (Satin Spar Selenite)

Satin Spar - Hydrous Calcium Sulfate (CaSO4·2H2O)

Hardness: 2 on Mohs scale (can be scratched by a fingernail). Color: Peach to orange-pink. Luster: Pearly to silky (satin-like). Crystal structure: Monoclinic, typically found in fibrous, parallel masses. Cleavage: Perfect in one direction.

Hardness: 2 on Mohs scale (can be scratched by a fingernail)
Color: Peach to orange-pink
Luster: Pearly to silky (satin-like)

Identified March 13, 2026More mineral →

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Physical properties

Formation & geological history

Formed as an evaporite mineral in sedimentary environments where seawater or saline groundwater evaporates. The orange color is usually due to the presence of trace amounts of hematite or iron oxides. Specimens can date from various geological periods, common in Mesozoic and Cenozoic deposits.

Uses & applications

Mostly used for ornamental purposes, such as carvings, lamps, and bowls. It is highly popular in the metaphysical and gem collecting community. Gypsum in general is used in the manufacture of drywall, plaster, and cement.

Geological facts

Despite being commonly called 'Selenite' in the trade, 'Satin Spar' is the technically correct term for this fibrous variety. It is so soft that it is water-soluble; if left in water for extended periods, it will eventually dissolve or lose its luster.

Field identification & locations

Identify in the field by its extreme softness (the 'fingernail test') and its fibrous, chatoyant appearance. Commonly found in Morocco, Mexico, and the United States (Utah/New Mexico). For collectors, avoid getting it wet and store it separately from harder stones to prevent scratching.

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