Selenite
Gypsum var. Selenite · Mineral Specimen / Decorative Stone
Crystal System
Monoclinic system, typically forming tabular, prismatic, or fibrous crystal habits with striated surfaces.
Mineral Group
Sulfates (specifically hydrated calcium sulfate)
Chemical Formula
CaSO4 · 2H2O
Formation Process
Sedimentary or evaporite formation process, occurring when bodies of high-salinity water evaporate in arid environments under low to moderate temperatures and pressures.
About This Crystal
The specimen is a translucent to transparent, white to colorless elongated crystal piece with a distinct fibrous or columnar structure. It exhibits a pearly to silky luster along cleavage planes and a vitreous luster on crystal faces, displaying characteristic linear striations.
Physical Characteristics
Color is colorless to white with a white streak. It has perfect pinacoidal cleavage in one direction, yielding very thin, flexible sheets. Fracture is uneven, specific gravity is approximately 2.30, and tenacity is sectile to flexible. It may show weak fluorescence under UV light.
Optical Properties
Biaxial (+) with refractive indices ranging between 1.520 and 1.530. Displays low birefringence and can exhibit a slight pearly chatoyancy or a cat's-eye effect due to its fibrous nature.
Hardness & Durability
Origin Region
Found globally with major deposits in Mexico (Naica), Morocco, Poland, USA (Utah, New Mexico), and Australia. Typically forms in evaporite deposits.
Hardness & Durability
Mohs hardness of 2 (very soft, easily scratched by a fingernail). Poor durability and very low wearability for jewelry due to extreme softness and perfect cleavage.
Care & Maintenance
Extremely soft and water-soluble; do not submerge in water or use liquid cleaners. Clean with a dry cloth only. Store separately from harder stones to avoid scratching and keep away from high humidity.
Rarity & Value
Common and widely available. Value is generally low to moderate depending on size, clarity, and form (such as carved shapes or large optical grade blocks). Treatments are rare.
Special Characteristics
Exhibits a silky fibrous chatoyancy and can display phosphorescence or fluorescence under specific UV lighting conditions. It is extremely soft and sensitive to moisture.
Lore & History
Named after the Greek goddess of the moon, Selene, due to its moon-like glow. Historically used in various decorative arts. In modern metaphysical practices, it is traditionally believed to cleanse and clear energy fields and charge other crystals, though these are cultural beliefs and not scientifically proven.