metamorphic
Nephrite Jade
Ca2(Mg,Fe)5Si8O22(OH)2 (Tremolite-Actinolite series)
Hardness: 6.0-6.5; Color: Varying shades of green, creamy white to yellow; Luster: Vitreous to greasy; Crystal Structure: Monoclinic (fibrous/interlocking microcrystalline structure); Specific Gravity: 2.9-3.0; Extremely tough due to interlocking fibers.
- Hardness
- 6
- Color
- Varying shades of green, creamy white to yellow
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 6.0-6.5; Color: Varying shades of green, creamy white to yellow; Luster: Vitreous to greasy; Crystal Structure: Monoclinic (fibrous/interlocking microcrystalline structure); Specific Gravity: 2.9-3.0; Extremely tough due to interlocking fibers.
Formation & geological history
Formed through contact metamorphism involving magnesium-rich limestones and acidic igneous rocks, or through the metamorphism of serpentine and mafic rocks. Often found in alluvial deposits or glacial till.
Uses & applications
Used extensively for ornamental carvings, jewelry (cabochons and beads), historical weapons (axe heads), and as a decorative architectural stone.
Geological facts
Nephrite is significantly tougher than steel because of its felted, interlocking crystal structure. It was highly prized in ancient China for ritual objects and was known as the 'Stone of Heaven'.
Field identification & locations
Identify in the field by its waxy-to-greasy luster when wet, extreme toughness (won't shatter easily under a hammer), and smooth feel. Common in riverbeds in British Columbia, New Zealand, and Wyoming.
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