Gem-quality, usually green silicate mineral in the tremolite-actinolite-ferrotremolite series of amphibole s.
It is the less prized but more common of the two types of jade and may be distinguished from jadeite by its splintery fracture and oily lustre. Nephrite occurs in low-grade (formed under low-temperature, low-pressure conditions), regionally metamorphosed rocks. Important deposits occur in China, Siberia, New Zealand, Switzerland, Alaska, and Wyoming.