Nephrite Jade
Image: James St. John (CC BY 2.0)
Mineral NameNephrite Jade
Chemical FormulaCa2(Mg,Fe)5Si8O22(OH)2 (Tremolite-Actinolite series)
Mohs Hardness6
Crystal Systemmonoclinic
Lustervitreous
Streak Colorwhite
CleavageNone (due to felted texture, though constituent amphiboles have perfect cleavage)
Fracturesplintery to fibrous
Specific Gravity2.95
Colorsgreen, white, yellow, brown, black
Transparencytranslucent to opaque
Type LocalityGranite Mountains, Wyoming, USA
Mineral GroupSilicates (Amphibole group)
Usesjewelry, carvings, tools, collector
Associated Mineralsserpentine, chlorite, talc, magnetite, chromite
Rarityuncommon
Description
This specimen is a dark green, ventifacted piece of nephrite jade, showing a smooth, weathered surface. Nephrite jade is a tough, dense metamorphic rock with a fine-grained, felted texture.
Geological Context
Nephrite jade is a metamorphic rock, primarily composed of tremolite-actinolite amphiboles, formed under high pressure and low temperature conditions, often associated with serpentinization. This specimen is from the Precambrian era in Wyoming, USA.
