metamorphic
Nephrite Jade
Tremolite-Actinolite solid solution Ca2(Mg,Fe)5Si8O22(OH)2
Hardness: 6.0-6.5 Mohs. Color: Deep green, grayish-green, or black. Luster: Vitreous to greasy. Crystal Structure: Monoclinic (interlocking fibrous structure). Specific Gravity: 2.90-3.03. Cleavage: Indistinct.
- Hardness
- 6
- Color
- Deep green, grayish-green, or black
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 6.0-6.5 Mohs. Color: Deep green, grayish-green, or black. Luster: Vitreous to greasy. Crystal Structure: Monoclinic (interlocking fibrous structure). Specific Gravity: 2.90-3.03. Cleavage: Indistinct.
Formation & geological history
Formed through the regional metamorphism of magnesium-rich limestones (dolostones) or serpentinites. It is commonly found in metamorphic terranes associated with subduction zones.
Uses & applications
Extensively used for jewelry, decorative carvings, ornamental sculptures, and historically for axes and weapons due to its extreme toughness.
Geological facts
Nephrite is valued more for its toughness than its hardness; its interlocking fibrous structure makes it more resistant to fracturing than diamond. It was known in ancient China as the 'Stone of Heaven.'
Field identification & locations
Identified by its waxy luster when polished and its extreme toughness. Found in British Columbia, New Zealand, Russia, and Wyoming. Field identification involves a scratch test and density check.
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