
metamorphic
Nephrite Jade
Tremolite-Actinolite series: Ca2(Mg,Fe)5Si8O22(OH)2
Hardness: 6-6.5 (Mohs), Color: Dark green to creamy white, Luster: Vitreous to greasy, Structure: Microcrystalline fibrous (interlocking), Specific Gravity: 2.9-3.0
- Hardness
- 6-6
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Physical properties
Hardness: 6-6.5 (Mohs), Color: Dark green to creamy white, Luster: Vitreous to greasy, Structure: Microcrystalline fibrous (interlocking), Specific Gravity: 2.9-3.0
Formation & geological history
Formed via regional metamorphism of magnesium-rich limestones or dolomites, or from the hydrothermal alteration of ultramafic rocks. Found in tectonic subduction zones globally.
Uses & applications
Highly prized for lapidary arts, jewelry, traditional carvings, and sculpture due to its extreme toughness/resistance to fracturing.
Geological facts
Nephrite is actually tougher (more resistant to breaking) than its cousin Jadeite because of its felted, interlocking needle-like crystal structure. It was once believed to cure kidney ailments.
Field identification & locations
Field identification involves checking for a greasy luster and high toughness; it is difficult to break with a hammer. Often found as water-worn cobbles in rivers. Check for translucency on thin edges.
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