metamorphic
Nephrite Jade
Nephrite (Ca2(Mg, Fe)5Si8O22(OH)2)
Hardness: 6-6.5 Mohs; Color: Mutton-fat white to spinach green, often translucent; Luster: Greasy to vitreous; Structure: Interlocking fibrous microcrystals (felted texture); Specific Gravity: 2.90-3.03.
- Hardness
- 6-6
- Color
- Mutton-fat white to spinach green, often translucent
- Luster
- Greasy to vitreous
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Physical properties
Hardness: 6-6.5 Mohs; Color: Mutton-fat white to spinach green, often translucent; Luster: Greasy to vitreous; Structure: Interlocking fibrous microcrystals (felted texture); Specific Gravity: 2.90-3.03.
Formation & geological history
Formed through contact metamorphism of magnesium-rich limestones (dolomites) or from the hydrothermal alteration of ultramafic rocks. Common in mountain belts and river deposits.
Uses & applications
Extensively used in fine jewelry, ornamental carvings, sculpture, and traditional cultural artifacts. Historically used for tool making (ax heads) due to its extreme toughness.
Geological facts
Nephrite is tougher than steel due to its interlocking fibrous structure, making it incredibly difficult to break. It was once believed to cure kidney ailments, which is why it is named after the Greek word 'nephros' for kidney.
Field identification & locations
Identify by its 'mutton-fat' or greasy feel and translucent edges when held to light. Found in riverbeds as water-worn cobbles. Major sources include New Zealand, British Columbia, and China.
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