Selenite
Gypsum var. Selenite · Mineral Specimen and Decorative Stone
Crystal System
Monoclinic. Typically forms tabular crystals, prismatic, or massive, fibrous aggregates. Twinning is common, often forming 'swallowtail' twins.
Mineral Group
Sulfates (specifically hydrated calcium sulfate)
Chemical Formula
CaSO4·2H2O
Formation Process
Sedimentary or evaporitic process. Forms through the evaporation of ancient seas, saline lakes, or hydrothermal waters where calcium and sulfate concentrations are high, precipitating out under low to moderate temperatures.
About This Crystal
The specimen is a columnar, polished block of white selenite exhibiting a distinct fibrous texture running longitudinally. It has a silky to pearly luster, translucent to semi-transparent clarity, and a milky-white body color with characteristic linear striations along the growth axis.
Physical Characteristics
Color is white to colorless. Streak is white. Perfect cleavage in one direction, yielding thin, flexible sheets. Fracture is uneven or fibrous. Specific gravity is approximately 2.3. Tenacity is sectile and flexible in thin flakes. Soft enough to be scratched by a fingernail.
Optical Properties
Biaxial (+) with refractive indices ranging from 1.520 to 1.530. Displays double refraction (birefringence). The fibrous habit can create a subtle chatoyant or silky light reflection (cat's eye effect) along the parallel fibers.
Hardness & Durability
Origin Region
Major deposits are found in Mexico (Naica Mine), Morocco, Poland, USA, and Australia. Forms primarily in sedimentary environments from evaporating sulfate-rich saline waters.
Hardness & Durability
Mohs hardness of 2, making it very soft. Extremely low durability, easily scratched, dented, or broken due to perfect cleavage. Poor choice for jewelry as it wears down easily and is sensitive to pressure.
Care & Maintenance
Water-soluble, so it must never be submerged in water or cleaned with liquid cleaners; wipe with a dry cloth only. Store away from moisture and harder minerals to prevent scratching. Sensitive to high humidity.
Rarity & Value
Common. Selenite is widely abundant globally, making specimens very affordable. Value depends mainly on size, clarity, and form, ranging from inexpensive tumbled stones to moderately priced large carved shapes. Generally untrodden and natural.
Special Characteristics
Exhibits a distinct silky luster due to its fibrous nature, giving it a glowing optical effect when light passes through the length of the crystal. It is also exceptionally soft and water-soluble.
Lore & History
Named after the Greek goddess of the moon, Selene, due to its moon-like glow. Historically used as a decorative material and in traditional window glass (called 'Aventurine' or 'Maria Glass' in ancient times). In modern crystal healing, it is traditionally believed to cleanse other crystals, clear negative energy, and promote mental clarity and peace.