Nephrite
Rock made of tremolite, actinolite
Uncommon · Ca₂(Mg,Fe)₅Si₈O₂₂(OH)₂
A rock of felted, microscopic fibres of tremolite and actinolite, so tough that it has made axes and blades since the Stone Age. Iron makes it green; nearly pure tremolite gives the white "mutton-fat" jade. It forms where serpentinite or dolomitic marble meets an intrusion, and is found as river and beach pebbles. The commoner of the two materials sold as jade.
Rock
- Kind of rock
- Metamorphic rock
- Rock family
- Ultramafic rock (peridotite, serpentinite)
- Deposits
- Placer deposit
- How it forms
- Forms where serpentinite or dolomitic marble meets other rocks and fluids.
- Uses
- Axes and blades since the Stone Age, then carving jade.
Identity
- Formula
- Ca₂(Mg,Fe)₅Si₈O₂₂(OH)₂
- Chemical class
- Silicate
- Part of
- Jade
- Mineral group
- Actinolite, Hornblende, Richterite, Tremolite
- Also known as
- Nephrite jade, Mutton-fat jade (white), Axe-stone
Crystallography
- Crystal system
- Monoclinic
- Habits
- Massive, Fibrous
- Fracture
- Splintery
Physical properties
- Mohs hardness
- 6
- Density
- 3 g/cm³
- Luster
- Vitreous
- Colors
- green, dark green, white, yellow, brown, gray, black
- Streak
- white
- Transparency
- Translucent, Opaque
Geology
- Origins
- Metamorphic
- Host rocks
- Ultramafic rock (peridotite, serpentinite), Marble, River gravels and sands
- Associated minerals
- Tremolite, Actinolite, Diopside, Grossular, Magnetite, Chromite, Serpentine
- Geography
- China, Canada (British Columbia), Russia, New Zealand, USA, Taiwan, Switzerland
Classification
- Rarity
- Uncommon
- Gem quality
- Yes
Sources
- Nephrite. Mindat.org (Hudson Institute of Mineralogy).
- Nephrite. Gemdat.org (Hudson Institute of Mineralogy).
- Jade. Gemological Institute of America, Gem Encyclopedia.
- Jade Description. Gemological Institute of America, Gem Encyclopedia.
- J. W. Anthony, R. A. Bideaux, K. W. Bladh, M. C. Nichols, Tremolite. Mineral Data Publishing, Handbook of Mineralogy, 2001.
- J. W. Anthony, R. A. Bideaux, K. W. Bladh, M. C. Nichols, Actinolite. Mineral Data Publishing, Handbook of Mineralogy, 2001.
- S. Robertson, BGS Rock Classification Scheme, Volume 2: Classification of metamorphic rocks (Research Report RR 99-02). British Geological Survey, 1999.
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