Satin Spar (Selenite)
Gypsum var. Satin Spar · Decorative Stone / Mineral Specimen
Crystal System
Monoclinic; typically exhibits a fibrous, columnar, or massive habit with elongated parallel crystals.
Mineral Group
Sulfates (Hydrous Calcium Sulfate)
Chemical Formula
CaSO4·2H2O (Calcium Sulfate Dihydrate)
Formation Process
Sedimentary process via the evaporation of saline water (seawater or groundwater in clay beds) or through hydrothermal activity in low-temperature veins.
About This Crystal
White to colorless translucent mineral with a distinct pearly to silky luster. It appears as a bundle of fine, parallel fibers that transmit light along their length.
Physical Characteristics
White body color, white streak. Perfect cleavage in one direction (micaceous). 2.32 Specific Gravity. Often shows weak fluorescence under UV light (usually blue or white).
Optical Properties
Biaxial (+) with refractive indices of 1.520–1.530. Exhibits strong fiber-optic properties (chatoyancy) where light reflects off the internal parallel fibers.
Hardness & Durability
Origin Region
Morocco (most common), Mexico (Naica), USA (Utah), and Brazil. Forms notably in evaporite sedimentary environments.
Hardness & Durability
Mohs hardness of 2. Very soft; can be scratched by a fingernail. Extremely fragile with poor toughness; sensitive to heat and impact.
Care & Maintenance
Keep dry as it is slightly water-soluble. Clean only with a dry soft cloth; avoid ultrasonic cleaners, steam, and chemicals. Store separately from harder stones.
Rarity & Value
Very common and affordable. Value is based on size and the 'whiteness' or cleanliness of the fibers. Usually sold in raw or polished 'wands'.
Special Characteristics
Strong chatoyant 'cat's eye' effect caused by the fibrous structure. It acts as a natural fiber optic, carrying light from one end of the wand to the other.
Lore & History
Named after the Greek word 'selene' (moon). Historically used as window panes in some ancient cultures. In metaphysical lore, it is believed to be a stone of mental clarity and energy cleansing.