Nephrite is a variety of the calcium, magnesium, and iron-rich amphibole minerals tremolite or actinolite. The chemical formula for nephrite is Ca₂(Mg, Fe)₅Si₈O₂₂(OH)₂. It is one of two different mineral species called jade. The other mineral species known as jade is jadeite, which is a variety of pyroxene. While nephrite jade possesses mainly grays and greens, jadeite jade, which is rarer, can also contain blacks, reds, pinks and violets. Nephrite jade is an ornamental stone used in carvings, beads, or cabochon cut gemstones. Nephrite is also the official state mineral of Wyoming.
Nephrite can be found in a translucent white to very light yellow form which is known in China as mutton fat jade, in an opaque white to very light brown or gray which is known as chicken bone jade, as well as in a variety of green colors. Western Canada is the principal source of modern lapidary nephrite. Nephrite jade was used mostly in pre-1800 China as well as in New Zealand, the Pacific Coast and Atlantic Coasts of North America, Neolithic Europe, and southeast Asia.