Nephrite is a rock of densely interlocked fibers of actinolite-tremolite, an amphibole. This fine-grained interlocking structure makes it very tough.
Properties
| Refractive index | 1.606 to 1.632 (+0.009/-0.006); shadow edge usually about 1.62 |
|---|---|
| Birefringence | Not measurable (an aggregate) |
| Optic character | Aggregate |
| Dispersion | Not given by our sources |
| Specific gravity | 2.95 |
| Hardness (Mohs) | 6.0 to 6.5 |
| Crystal system | Aggregate (monoclinic) |
| Pleochroism | Not recorded |
| Absorption spectrum | Not recorded |
Published values. They change a little from stone to stone. Our tools do not model nephrite yet. Sources: GIA · International Gem Society
In more detail
Gem nephrite is commonly white to deep green, but it can also be brown or black. Chromium and iron cause the green color of nephrite. It is a little softer than jadeite, but both resist breaking and chipping very well.
On a grading report
LMHC wording: Group: amphibole. Species: (natural) actinolite-tremolite. Variety: (color) nephrite (jade).
Related terms
- Jade: Jade is a trade name for gem rocks made mainly of jadeite or nephrite. Their tiny interlocking crystals make them exceptionally tough.
- Jadeite: Jadeite is a pyroxene mineral, and jadeite jade is a rock of its aggregated fibrous or granular crystals. Chromium causes the color of green jadeite.
- Toughness: Toughness is a gem's resistance to chipping and breaking. It differs from hardness, which is resistance to scratching.
- Hardness (Mohs): Hardness is a gem's resistance to scratching. Gemologists rank it on the Mohs scale, on which diamond is 10.