a gem-quality silicate mineral in the tremolite–actinolite series of amphiboles. It is the less prized but more common of the two types of jade, usually found as translucent to opaque, compact, dense aggregates of finely interfelted tufts of long, thin fibres. It may be distinguished from jadeite (q.v.), jade's other form, by its splintery fracture and oily lustre. Ordinarily coloured green, nephrite is commonly mottled or flecked with dark inclusions.

Nephrite occurs in low-grade, regionally metamorphosed rocks. China's most important source of nephrite throughout history has been the region of Khotan (Ho-t'ien) and Yarkand in central Asia. Other important sources include the Lake Baikal area, Siberia; South Island, New Zealand; near Kotzebue, Alaska; along the Sweetwater River, Wyoming; and the canton of Graubünden, Switzerland. Great boulders of nephrite have been found near Jordanów (Jordansmühl) in Silesia, Poland, and in the valleys of the Turnagain and Fraser rivers in British Columbia. Nephrite was found in 1960 at Mashaba, Rhodesia, the first find on the African continent. In 1965 the mineral was found near Hualien, Taiwan (Formosa).