metamorphic
Nephrite Jade
Nephrite (Ca2(Mg, Fe)5Si8O22(OH)2)
Hardness: 6-6.5 (Mohs); Color: Pale to dark green, grayish; Luster: Vitreous to greasy; Crystal structure: Monoclinic (fibrous/interlocking); Cleavage: Indistinct; Specific gravity: 2.9-3.03
- Hardness
- 6-6
- Color
- Pale to dark green, grayish
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 6-6.5 (Mohs); Color: Pale to dark green, grayish; Luster: Vitreous to greasy; Crystal structure: Monoclinic (fibrous/interlocking); Cleavage: Indistinct; Specific gravity: 2.9-3.03
Formation & geological history
Formed through the metamorphism of magnesium-rich limestones (dolomites) or the alteration of ultramafic igneous rocks (serpentinite) in subduction zones.
Uses & applications
Used extensively in jewelry, ornamental carvings, statues, and historically for durable tool-making (ax heads).
Geological facts
Nephrite is one of two distinct minerals known as jade, the other being jadeite. It is exceptionally tough due to its interlocking fibrous structure, making it harder to break than steel or granite.
Field identification & locations
Identify in the field by its waxy/greasy luster when wet or polished, its extreme toughness, and common occurrence in beach or river gravels in specific geological regions like California (Jade Cove), British Columbia, or New Zealand.
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