Jade
Image: James St. John (CC BY 2.0)
Mineral NameJade
Chemical FormulaCa₂(Mg,Fe)₅Si₈O₂₂(OH)₂
Mohs Hardness6
Crystal Systemmonoclinic
Lustervitreous
Streak Colorwhite
Cleavagegood in two directions at ~56° and 124° (for constituent amphiboles)
Fracturesplintery
Specific Gravity3
Colorsdark green, yellowish-green, brownish-green
Transparencytranslucent
Type LocalityGranite Mountains, Wyoming, USA
Mineral GroupSilicates
Usesjewelry, carving, ornamental objects, collector
Associated Mineralstremolite, actinolite
Raritycommon
Description
This specimen is a large, irregularly shaped piece of nephrite jade, displaying a mottled appearance with shades of dark green, yellowish-green, and brownish tones, and a somewhat rough, ventifacted surface.
Geological Context
Nephrite jade is a metamorphic rock formed from the alteration of ultramafic rocks or dolomitic limestones under high pressure and relatively low temperature conditions, typically found in subduction zones or regional metamorphic terrains. This specimen is from the Precambrian of Wyoming.
