metamorphic
Nephrite Jade
Ca2(Mg, Fe)5Si8O22(OH)2
Hardness: 6-6.5 (Mohs); Color: Spinach green to deep olive green; Luster: Vitreous to greasy; Crystal Structure: Monoclinic (fibrous aggregate); Cleavage: Distinct but usually not visible due to interlaced structure; Specific Gravity: 2.90-3.03.
- Hardness
- 6-6
- Color
- Spinach green to deep olive green
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 6-6.5 (Mohs); Color: Spinach green to deep olive green; Luster: Vitreous to greasy; Crystal Structure: Monoclinic (fibrous aggregate); Cleavage: Distinct but usually not visible due to interlaced structure; Specific Gravity: 2.90-3.03.
Formation & geological history
Formed via metasomatism in contact metamorphism between ultramafic rocks and lime-rich rocks or through subduction zone metamorphism. Found in various geological ages ranging from Precambrian to Mesozoic.
Uses & applications
Used widely in ornamental carvings, jewelry (cabochons, beads), axe heads in prehistoric times, and decorative objects.
Geological facts
Nephrite is significantly tougher than diamond in terms of fracture resistance because of its tightly interlocking fibrous structure. It was highly prized by the Māori people of New Zealand, who called it Pounamu.
Field identification & locations
Identify by its 'greasy' feel when polished and its extreme toughness. It is common in riverbeds and mountainous regions of British Columbia, Russia, and New Zealand. It will not be scratched by a steel knife but is softer than quartz.
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