metamorphic
Nephrite Jade
Tremolite-Actinolite solid solution Ca2(Mg,Fe)5Si8O22(OH)2
Hardness: 6-6.5 Mohs. Color: Deep green to olive. Luster: Vitreous to greasy (waxy when polished). Crystal structure: Monoclinic (felted interlocking fibrous structure). Cleavage: Indistinct. Specific gravity: 2.90–3.03.
- Hardness
- 6-6
- Color
- Deep green to olive
- Luster
- Vitreous to greasy (waxy when polished)
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Physical properties
Hardness: 6-6.5 Mohs. Color: Deep green to olive. Luster: Vitreous to greasy (waxy when polished). Crystal structure: Monoclinic (felted interlocking fibrous structure). Cleavage: Indistinct. Specific gravity: 2.90–3.03.
Formation & geological history
Formed through contact metamorphism of magnesium-rich limestones (dolomite) or the metamorphism of serpentinite rocks. This specific river-worn cobble indicates it was eroded from its primary source and tumbled in water.
Uses & applications
Used extensively in jewelry (cabochons, beads), decorative carvings, high-end tiling, and as a durable material for handheld tools in ancient cultures due to its extreme toughness.
Geological facts
Nephrite is famous for its 'toughness' rather than 'hardness'; it is more difficult to break than diamond because of its interlocking fibrous structure. It was highly prized in Neolithic China and Maori culture.
Field identification & locations
Identify in the field by its dark green color, heavy weight for its size, and 'soapy' feel. It is commonly found in alluvial deposits (riverbeds) in British Columbia, New Zealand, Alaska, and Russia.
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