metamorphic
Nephrite Jade
Tremolite-Actinolite series (Ca2(Mg,Fe)5Si8O22(OH)2)
Hardness: 6-6.5 on Mohs scale; Color: light to dark green, yellowish green, tan; Luster: waxy to greasy; Crystal structure: monoclinic (interlocking fibrous microcrystalline mass); Cleavage: none (tough, splintery fracture); Specific gravity: 2.9-3.0
- Hardness
- 6-6
- Color
- light to dark green, yellowish green, tan
- Luster
- waxy to greasy
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Physical properties
Hardness: 6-6.5 on Mohs scale; Color: light to dark green, yellowish green, tan; Luster: waxy to greasy; Crystal structure: monoclinic (interlocking fibrous microcrystalline mass); Cleavage: none (tough, splintery fracture); Specific gravity: 2.9-3.0
Formation & geological history
Formed through regional metamorphic processes involving ultra-mafic rocks or dolomitic limestones under moderate heat and pressure, often found in serpentinite belts along subduction zones.
Uses & applications
Used extensively in carving, jewelry, cabochons, decorative sculptures, and historically in tools and weapons due to its extreme toughness.
Geological facts
Nephrite is famous for being exceptionally tough, even tougher than steel, due to its tightly interwoven fibrous crystal structure. It was highly prized in ancient China and Maori cultures of New Zealand.
Field identification & locations
Identified by its waxy-greasy luster, high toughness, smooth soapy feel when polished, and green hues with brownish-yellow weathered crusts. Commonly found in California, Wyoming, British Columbia, New Zealand, and Russia.
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