Quick Facts
Formation & Origin
Nephrite is a variety of actinolite-tremolite composed of densely interlocking microscopic fibers. This interlocking structure gives nephrite its extraordinary toughness, making it the toughest natural material known (tougher even than steel in terms of resistance to breaking).
It forms through metasomatic alteration of serpentinite or dolomitic marble. When silica-rich fluids interact with magnesium-rich ultramafic rocks or carbonate rocks, the resulting chemical reactions produce amphibole minerals that grow as tightly interwoven fibers. Iron content determines color: more iron produces darker greens and blacks, while iron-poor nephrite can be nearly white.
The white 'mutton fat' nephrite from Hotan, China has been prized for over 7,000 years and remains among the most valuable jade varieties. In Chinese culture, nephrite was jade for millennia before jadeite (the other jade mineral) was imported from Myanmar in the 18th century.
Identification Guide
Nephrite is identified by its waxy to greasy luster, exceptional toughness (it's very difficult to break), and characteristic colors. Under magnification, the fibrous structure is visible. Specific gravity of 2.90-3.03 is lower than jadeite (3.30-3.38).
Distinguish from jadeite (higher SG, more vitreous luster, often more translucent), serpentine (softer at 3-5, lower SG), and aventurine (sparkly inclusions, quartz family). A simple test: nephrite is so tough that it's virtually impossible to break by hand.
Spotting Fakes
The jade market is rife with imitations. Serpentine ('new jade'), dyed quartzite, glass, and plastic are all sold as jade. For nephrite specifically: check specific gravity (2.90-3.03), look for fibrous structure under magnification, and test toughness (genuine nephrite resists scratching and chipping). Dyed material can be detected with a Chelsea color filter or by checking for dye concentration in fractures. B-jade (acid-bleached and polymer-impregnated) is an issue primarily with jadeite rather than nephrite.
Cultural & Metaphysical Traditions
Presented as cultural traditions, not scientific evidence
Nephrite jade has been revered in Chinese culture for thousands of years as the 'stone of heaven,' associated with wisdom, purity, and moral integrity. The Maori of New Zealand consider pounamu (nephrite) a taonga (treasure) with deep spiritual significance. In Western crystal healing, nephrite is connected to the heart chakra, emotional balance, and protection.
Where It's Found
Prized white 'mutton fat' nephrite, imperial jade source
Sacred Maori greenstone, legally protected
World's largest modern producer by volume
Fine spinach-green nephrite
Price Guide
Good to Know
Scratch test: At hardness 6, Nephrite resists scratching from a knife but can be scratched by quartz. Best for pendants and earrings rather than rings.
Sources: Found in 4 notable locations worldwide, from China to Russia.
Heft test: Nephrite has average mineral density (2.90-3.03). It feels about as heavy as you'd expect from a stone its size.
Related Minerals
The other 'jade' mineral, a pyroxene
Parent mineral, nephrite is the fibrous variety
Common jade imitation, similar colors