British Columbia, Canada, is the principal commercial source of nephrite jade in the world by tonnage, supplying the bulk of the rough that feeds the Chinese, Hong Kong and Taiwanese carving industries. The deposits run along the Cordillera through the central and northern interior of the province, with the Cassiar, Mount Ogden, Polar (Dease Lake), Kutcho and Provencher Lake mines as the principal historical and current operations. British Columbia nephrite is given the official provincial-gemstone status by the Government of British Columbia.

Geology

The British Columbia nephrite deposits occur as serpentinite-hosted lenses formed by the metasomatic alteration of ultramafic rocks at greenschist-facies metamorphic grade, typically in the contact zones between serpentinised peridotite bodies and adjacent rodingitised gabbros or ophiolite-related country rock. The mineralogy is the standard nephrite assemblage — felted tremolite-actinolite with subsidiary chlorite, talc and chromite — and the characteristic dark to medium spinach-green colour derives from iron substitution in the actinolite component. Boulder, vein and float deposits are all worked.

Mining history

Industrial extraction began in the 1960s, with the first major shipments to the Hong Kong carving market in 1968. Cassiar Asbestos Corporation (later Cassiar Mining) was an early producer, finding nephrite as a by-product of asbestos mining. The Polar Mines operation in the Dease Lake area, run by the Schmidt family of Vancouver, has been a continuous producer since the 1970s. Annual production from the province has historically run between 150 and 500 tonnes of marketable rough depending on demand cycles, with the bulk shipped through Vancouver and Prince Rupert to Hong Kong and Beijing.

Quality and use

British Columbia nephrite is generally a medium to dark green of moderate translucency, with the highest grades approaching the historical Hetian standard but rarely matching the white "mutton-fat" tradition of the Tarim Basin sources. The material is used principally for carved decorative objects — statuary, dragons, screens, panels and the larger sculptural pieces of the Beijing and Shanghai carving market — and to a lesser extent for cabochon, bead and bangle work. The toughness of nephrite makes it the dominant material for the Chinese-export carving trade in figures and the source of the so-called "BC nephrite" or "Canadian jade" of the wholesale carved-jade market.

Trade and ownership

The province's First Nations communities, in whose traditional territories most of the deposits sit, have increasingly entered the trade as joint-venture partners and direct operators since the 2010s. The Tahltan, Kaska Dena and Tsay Keh Dene nations are among those with negotiated arrangements covering nephrite exploration and extraction. The provincial government regulates jade as a commercial mineral under the Mineral Tenure Act, and the trade is supported by the British Columbia Jade and Mineral Producers Association.