jade: A hard semiprecious stoneconsisting either of jadeite ornephrite. Jadeite, the most valued ofthe two, is a sodium aluminium pyroxene,NaAlSi2O6. It is prized for itsintense translucent green colour butwhite, green and white, brown, andorange varieties also occur. The onlyimportant source of jadeite is in theMogaung region of upper Burma.Nephrite is one of the amphibolegroup of rock-forming minerals. Itoccurs in a variety of colours, includinggreen, yellow, white, and black.Sources include the Siberia, Turkistan,New Zealand, Alaska, China,and W USA.
