metamorphic
Nephrite Jade
Ca2(Mg, Fe)5Si8O22(OH)2
Hardness: 6-6.5 (Mohs scale); Color: Dark green to black with lighter mottling; Luster: Vitreous to greasy; Crystal structure: Monoclinic (fibrous/interlocking microcrystals); Cleavage: Indistinct; Specific gravity: 2.9-3.03.
- Hardness
- 6-6
- Color
- Dark green to black with lighter mottling
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 6-6.5 (Mohs scale); Color: Dark green to black with lighter mottling; Luster: Vitreous to greasy; Crystal structure: Monoclinic (fibrous/interlocking microcrystals); Cleavage: Indistinct; Specific gravity: 2.9-3.03.
Formation & geological history
Formed through the regional metamorphism of magnesium-rich limestones (dolostones) or serpentinites. It is an interlocking fibrous variety of tremolite-actinolite amphibole.
Uses & applications
Commonly used in jewelry, ornamental carvings, sculpture, and historically for durable tools like axe heads due to its extreme toughness.
Geological facts
Nephrite is famous for its toughness, which is even higher than diamond, meaning it is very difficult to break or shatter despite being less hard. It has been used for over 5,000 years in China.
Field identification & locations
Identify in the field by its soapy or greasy feel when polished and its extreme toughness against hammer strikes. Commonly found in British Columbia, New Zealand (Pounamu), Russia, and Wyoming.
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