metamorphic
Nephrite Jade
Nephrite (Ca2(Mg, Fe)5Si8O22(OH)2)
Hardness: 6.0-6.5 on Mohs scale; Color: Deep olive green to dark spinach green with cloudy mottling; Luster: Vitreous to greasy; Structure: Interlocking microcrystalline fibrous structure; Cleavage: None (highly tough fracture); Specific Gravity: 2.90-3.03.
- Hardness
- 6
- Color
- Deep olive green to dark spinach green with cloudy mottling
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 6.0-6.5 on Mohs scale; Color: Deep olive green to dark spinach green with cloudy mottling; Luster: Vitreous to greasy; Structure: Interlocking microcrystalline fibrous structure; Cleavage: None (highly tough fracture); Specific Gravity: 2.90-3.03.
Formation & geological history
Formed via contact metamorphism of magnesium-rich limestones (dolomites) or through the alteration of ultramafic rocks by hydrothermal fluids. Specimens often range from Mesozoic to Cenozoic geological ages.
Uses & applications
Used extensively in jewelry (cabochons, beads), small sculptures, ornamental carvings, and historical tool-making (axes, blades) due to its extreme toughness.
Geological facts
Nephrite is significantly tougher than steel due to its densely interwoven fibrous crystal structure. It was referred to as 'Lapis Nephriticus' by early Europeans who believed it could cure kidney ailments.
Field identification & locations
Identify in the field by its high density, greasy feel when polished, and extreme resistance to breaking. Commonly found in British Columbia, New Zealand, Siberia, and Wyoming. Unlike quartz, it will not crumble easily under high pressure.
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