metamorphic
Nephrite Jade
Nephrite (Ca2(Mg, Fe)5Si8O22(OH)2)
Hardness: 6.0-6.5 (Mohs); Color: Dark forest green to mottled black/green; Luster: Greasy to vitreous; Crystal structure: Monoclinic (fibrous interlocking aggregate); Cleavage: None (highly tough fracture); Specific Gravity: 2.90–3.03
- Hardness
- 6
- Color
- Dark forest green to mottled black/green
- Luster
- Greasy to vitreous
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Physical properties
Hardness: 6.0-6.5 (Mohs); Color: Dark forest green to mottled black/green; Luster: Greasy to vitreous; Crystal structure: Monoclinic (fibrous interlocking aggregate); Cleavage: None (highly tough fracture); Specific Gravity: 2.90–3.03
Formation & geological history
Formed through contact metamorphism or metasomatism of ultramafic rocks or dolomitic limestones, often associated with subduction zones. Can be found as river-worn cobbles (alluvial) or in situ deposits.
Uses & applications
Extensively used for ornamental carvings, jewelry (cabochons and beads), and historically for tools/weapons due to its extreme toughness.
Geological facts
Nephrite is actually tougher and more fracture-resistant than steel because of its interlocking felt-like fibrous structure. It has been used for over 5,000 years in China and was known as the 'Stone of Heaven'.
Field identification & locations
Identify in the field by its high density, 'waxy' or greasy feel when wet, and smooth, rounded surface as a river stone. It is often found in riverbeds in British Columbia, Alaska, and New Zealand (Pounamu).
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