metamorphic
Nephrite Jade (River Bed Pebble)
Nephrite (Ca2(Mg, Fe)5Si8O22(OH)2)
Hardness: 6-6.5 on Mohs scale. Color: Deep spinach green to blackish-green. Luster: Vitreous to greasy when polished. Crystal Structure: Monoclinic (fibrous interlocking structure). Cleavage: None (highly resistant to fracturing). Specific Gravity: 2.9–3.0.
- Hardness
- 6-6
- Color
- Deep spinach green to blackish-green
- Luster
- Vitreous to greasy when polished
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Physical properties
Hardness: 6-6.5 on Mohs scale. Color: Deep spinach green to blackish-green. Luster: Vitreous to greasy when polished. Crystal Structure: Monoclinic (fibrous interlocking structure). Cleavage: None (highly resistant to fracturing). Specific Gravity: 2.9–3.0.
Formation & geological history
Formed through the regional metamorphism of magnesium-rich limestones (dolomites) or ultramafic rocks. This specific specimen shows alluvial smoothing, indicating it was transported and polished by river action over thousands of years.
Uses & applications
Extensively used in fine jewelry, ornamental carvings, and historical weaponry (due to its extreme toughness). It is a staple in Asian art and modern lapidary work.
Geological facts
Nephrite is actually tougher (more resistant to breaking) than diamond because of its dense, interlocking felt-like fibrous structure. It has been used for over 5,000 years, notably in China where it is considered 'the stone of heaven'.
Field identification & locations
Identify in the field by its high density, waxy feel, and extreme toughness (it will not easily chip). Common locations include British Columbia (Canada), New Zealand, Wyoming (USA), and Russia. Collectors should look for translucency in thin edges when held to light.
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