metamorphic
Nephrite Jade
Tremolite-Actinolite solid solution Ca2(Mg, Fe)5Si8O22(OH)2
Hardness: 6-6.5 Mohs; Color: Dark green to blackish-green; Luster: Vitreous to greasy; Crystal Structure: Monoclinic (fibrous aggregates); Cleavage: Indistinct; Specific Gravity: 2.9-3.0
- Hardness
- 6-6
- Color
- Dark green to blackish-green
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 6-6.5 Mohs; Color: Dark green to blackish-green; Luster: Vitreous to greasy; Crystal Structure: Monoclinic (fibrous aggregates); Cleavage: Indistinct; Specific Gravity: 2.9-3.0
Formation & geological history
Formed via regional metamorphism or metasomatism of magnesium-rich rocks (ultramafic) or dolomitic limestones, often involving hydrothermal fluids.
Uses & applications
Used extensively in jewelry, ornamental carvings, sculpture, and historically for tool making due to its high toughness.
Geological facts
Nephrite is famous for its extreme toughness, which resides in its interlocking fibrous microstructure, making it harder to break than steel or diamond in terms of impact resistance.
Field identification & locations
Identify by its greasy luster, smoothness when tumbled, and extreme toughness. Commonly found in British Columbia, New Zealand, Russia, and Wyoming. Unlike Jadeite, it is usually deeper green and less translucent.
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