Jadeite and nephrite have distinctly different mineral compositions. Jadeite is an aluminum-rich pyroxene, while nephrite is a magnesium-rich amphibole. However, the two minerals have very similar physical properties in the eye of the average person.
Only trained observers with significant experience are able to reliably differentiate them without mineral testing equipment. This is why jadeite and nephrite were not properly distinguished by scientists until 1863.
Experienced gemologists can easily separate jadeite from nephrite in small polished items such as beads and cabochons. There are significant differences in their refractive index and specific gravity.
| Physical Properties: Jadeite and Nephrite | ||
| Jadeite | Nephrite | |
| Chemistry | Silicate – pyroxene. | Silicate – amphibole. |
| Color | Usually various shades of white to dark green, sometimes gray, pink, lilac, red, blue, yellow, orange, black, colored by impurities. | Usually ranges in color between white, cream, and dark green. |
| Streak | Colorless. | Colorless. |
| Luster | Vitreous to sugary. | Vitreous, greasy, silky, waxy. |
| Diaphaneity | Translucent to opaque. Rarely semi-transparent. | Translucent to opaque. Rarely semi-transparent. |
| Cleavage | Usually not seen because of a small grain size and splintery fracture. | Prismatic but usually not seen because of a small grain size and splintery fracture. |
| Mohs Hardness | 6.5 to 7 | 6 to 6.5 |
| Specific Gravity | 3.3 to 3.5 | 3.0 to 3.3 |
| Diagnostic Properties | Refractive index, toughness, hardness, specific gravity, grain size and habit. | Color, toughness, hardness, specific gravity, grain size, and habit. |
| Chemical Formula | NaAlSi2O6 or Na(Al,Fe3+)Si2O6 | Ca2(Mg,Fe)5Si8O22(OH)2 |
| Crystal System | Monoclinic. | Monoclinic. |
| Refractive Index | 1.66 to 1.68 (1.66 spot) | 1.60 to 1.63 (1.61 spot) |
| Uses | Jewelry, ornaments, tools, weapons, gemstones. | Jewelry, ornaments, tools, weapons, gemstones. |