metamorphic
Nephrite Jade
Ca2(Mg, Fe)5Si8O22(OH)2 (Tremolite-Actinolite series)
Hardness: 6-6.5 Mohs; Color: Deep forest green with occasional black inclusions; Luster: Vitreous to greasy; Crystal Structure: Monoclinic (fibrous interlocking structure); Specific Gravity: 2.9-3.03
- Hardness
- 6-6
- Color
- Deep forest green with occasional black inclusions
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 6-6.5 Mohs; Color: Deep forest green with occasional black inclusions; Luster: Vitreous to greasy; Crystal Structure: Monoclinic (fibrous interlocking structure); Specific Gravity: 2.9-3.03
Formation & geological history
Formed via regional or contact metamorphism of magnesium-rich limestones or dolomites, or from the hydrothermal alteration of mafic or ultramafic igneous rocks. Most significant deposits are Precambrian to Mesozoic in age.
Uses & applications
Ornamental carvings, cabochons for jewelry, historical tool-making, and as a popular stone for collectors of tumbled or polished minerals.
Geological facts
Nephrite is famous for its extreme toughness due to its interlocking fibrous structure, making it harder to break than steel of the same density. It has been used for over 5,000 years in Chinese culture as 'the Stone of Heaven'.
Field identification & locations
Identify by its characteristic greasy luster when polished and its cool feel to the touch. It is often found in riverbeds as water-worn cobbles near metamorphic serpentine belts. Locations include British Columbia, New Zealand, Russia, and Wyoming.
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