metamorphic
Nephrite Jade
Ca2(Mg, Fe)5Si8O22(OH)2 (Tremolite-Actinolite series)
Hardness: 6-6.5 Mohs; Color: Muted green to olive (due to iron content); Luster: Vitreous to greasy; Crystal structure: Monoclinic (fibrous/interlocking microcrystals); Specific gravity: 2.9-3.0; Cleavage: None (highly tough due to texture).
- Hardness
- 6-6
- Color
- Muted green to olive (due to iron content)
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 6-6.5 Mohs; Color: Muted green to olive (due to iron content); Luster: Vitreous to greasy; Crystal structure: Monoclinic (fibrous/interlocking microcrystals); Specific gravity: 2.9-3.0; Cleavage: None (highly tough due to texture).
Formation & geological history
Formed through the regional metamorphism of magnesium-rich carbonate rocks (dolomite) or the hydrothermal alteration of mafic/ultramafic igneous rocks (serpentine). They are typically found in mountain belts and subduction zones.
Uses & applications
Used extensively in jewelry (cabochons, beads), decorative carvings, sculpture, and historically for durable tool-making (axes) due to its extreme toughness.
Geological facts
Nephrite is actually tougher than steel in terms of fracture resistance because its internal crystals are woven together like felt. It was only distinguished from Jadeite in 1863 by French mineralogist Alexis Damour.
Field identification & locations
Identify by its 'greasy' feel when polished and high translucency compared to common green stones like jasper. Commonly found in British Columbia (Canada), New Zealand (Pounamu), Russia, and Wyoming (USA).
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