Nephrite

nephrite: see jade.

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nephrite

Gem-quality, usually green silicate mineral in the tremolite-actinolite-ferrotremolite series of amphiboles. 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.

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nephrite [ne′frīt]

(mineralogy)

An exceptionally tough, compact, fine-grained, greenish or bluish amphibole constituting the less valuable type of jade; formerly worn as a remedy for kidney diseases. Also known as greenstone; kidney stone.

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Nephrite 

(Greek nephros, “kidney”; in antiquity it was believed to be a remedy for kidney disease), a mineral variety of actinolite and tremolite, occurring as a compact microcrystalline aggregate with a minutely fibrous, felted structure. Extremely tough, nephrite readily acquires a polish. Its color varies from milky white or greenish to dark green, sometimes exhibiting mottled patterns owing to the inclusion of other minerals. It has been valued as a semiprecious stone since antiquity; tools and art objects have been fashioned out of it in various countries, particularly China, Burma, and India.

Nephrite is formed during the metamorphism of basic rocks, such as serpentinites and pyroxene and amphibole schists. It is generally extracted from alluvial deposits, where it occurs in the form of pebbles and large boulders. Major deposits of the mineral are found in the USSR (Vostochnyi Saian, the Baikal Region), China (Kunlun Mountains, basins of the Ho-t’ien and Yarkand rivers), New Zealand, and Polynesia.