metamorphic
Nephrite Jade
Tremolite-Actinolite solid solution (Ca2(Mg,Fe)5Si8O22(OH)2)
Hardness: 6.0-6.5 (Mohs); Color: Dark olive green to deep forest green; Luster: Greasy to waxy when polished, dull when raw; Cleavage: None (exceptionally tough due to interlocking fibrous structure); SG: 2.9-3.0.
- Hardness
- 6
- Color
- Dark olive green to deep forest green
- Luster
- Greasy to waxy when polished, dull when raw
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Physical properties
Hardness: 6.0-6.5 (Mohs); Color: Dark olive green to deep forest green; Luster: Greasy to waxy when polished, dull when raw; Cleavage: None (exceptionally tough due to interlocking fibrous structure); SG: 2.9-3.0.
Formation & geological history
Formed through the metamorphism of magnesium-rich limestones (dolomites) or from the alteration of mafic and ultramafic rocks. Found in contact metamorphic zones and as water-worn cobbles in riverbeds.
Uses & applications
Highly prized for ornamental carvings, jewelry, and historical weapon making due to its extreme toughness and fracture resistance.
Geological facts
Nephrite is tougher than steel, making it historically useful for axe heads and blades. Jade was once thought to cure kidney ailments, which is how it earned the name 'nephrite' (from the Greek 'nephros' for kidney).
Field identification & locations
Identify in the field by its characteristic 'greasy' feel when wet/polished, its extreme weight-to-size ratio, and its inability to be scratched by a common steel knife. Common in British Columbia, California, and New Zealand.
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