metamorphic
Nephrite Jade
Nephrite (Ca2(Mg, Fe)5Si8O22(OH)2)
Hardness: 6.0–6.5 (Mohs); Color: Pale to dark green (spinach green), grey-green, or brownish; Luster: Vitreous to greasy; Crystal structure: Monoclinic (felted interlocking fibrous habit); Cleavage: Prismatic, but rarely seen due to toughness; Specific Gravity: 2.90–3.03.
- Hardness
- 6
- Color
- Pale to dark green (spinach green), grey-green, or brownish
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 6.0–6.5 (Mohs); Color: Pale to dark green (spinach green), grey-green, or brownish; Luster: Vitreous to greasy; Crystal structure: Monoclinic (felted interlocking fibrous habit); Cleavage: Prismatic, but rarely seen due to toughness; Specific Gravity: 2.90–3.03.
Formation & geological history
Formed through the regional or contact metamorphism of serpentinite (metasomatism) or magnesium-rich limestones/dolomites. It is commonly found in association with ultramafic rocks and subduction zones.
Uses & applications
Extensively used in lapidary work for carvings, ornaments, and jewelry (cabochons and beads). Historically used for axe heads and weapons due to its extreme toughness and resistance to fracturing.
Geological facts
Nephrite is one of two distinct minerals called 'Jade' (the other being Jadeite). While Jadeite is harder, Nephrite is significantly tougher because of its interlocking fibrous structure, making it the most fracture-resistant natural stone in the world.
Field identification & locations
Identify in the field by its characteristic waxy or greasy luster when polished or water-worn, and its high density. Common locations include British Columbia (Canada), New Zealand, China, and Wyoming (USA). It is often found as river-worn boulders or pebbles.
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