Abstract Some sediment-hosted base metal deposits, specifically, the clastic-dominated Zn-Pb deposits, carbonatehosted Mississippi Valley-type (MVT) deposits, sedimentary rock-hosted stratiform copper deposits, and carbonate-hosted polymetallic (“Kipushi-type”) deposits, are or have been important sources of critical elements including Co, Ga, Ge, PGEs, and Re. Cobalt is noted in only a few clastic-dominated and MVT deposits, whereas sedimentary rock-hosted stratiform copper deposits are major producers. Gallium occurs in sphalerite from clastic-dominated and MVT deposits. Little is reported of germanium in clastic-dominated deposits; it is more commonly noted in MVT deposits (up to 4,900 ppm within sphalerite) and has been produced from carbonate-hosted polymetallic deposits (Kipushi, Tsumeb). Indium is known to be elevated in sphalerite and zinc concentrates from some MVT and clastic-dominated deposits, produced from Rammelsberg and reported from Sullivan, Red Dog, Tri-State, Viburnum Trend, Lisheen, San Vincente, and Shalipayco. Platinum and palladium have been produced from sedimentary rock-hosted stratiform copper deposits in the Polish Kupferschiefer. Sedimentary rock-hosted stratiform copper deposits in the Chu-Sarysu basin are known to have produced rhenium. Although trace element concentrations in these types of sediment-hosted ores are poorly characterized in general, available data suggest that there may be economically important concentrations of critical elements yet to be recognized.

Abstract The Nanisivik project is in the eastern Canadian Arctic at latitude 73° N, about 750 km north of the Arctic Circle. Winters are long and cold but temperature extremes are moderated by proximity to the Arctic and Atlantic oceans. Permafrost extends to depths of 500 m or more, and rock temperatures in the mine average minus 12° Celsius (McNeil et al, 1993). The area is a dry semi-desert with annual precipitation of 125 mm. Vegetation is sparse. Good surface rock exposure is limited to cliffs and creek beds since the more gentle slopes are covered by felsenmeer and glacial deposits. Nanisivik has proven to be a low-cost producer despite its location. It is accessible to ocean shipping which reduces transport costs, and the deposit geology is amenable to efficient mining and milling methods. Annual output is about 100,000 tonnes of concentrate containing 55 % zinc, produced from 750,000 tonnes of mined ore. Most of the ore is mined from room and pillar stopes using wheeled equipment. The project supports a community of 350 people, which includes a school, recreational facilities, and a jet airport. The mine staff comes from all over Canada and includes about 25 % Northerners. Most people go “out” on vacation two or three times a year. The marine waters around Greenland and the Canadian Arctic Islands have supported a meager Eskimo population for thousands of years. European exploration started with the Norsemen in medieval times but contact was limited by the extreme distances and short seasons of open water. Except for scattered trading posts, there was little settlement or development in the Islands until air travel became practical. Mineralization was first reported in the Nanisivik area by a prospector from a Coast Guard expedition that wintered over in Arctic Bay, 30 km to the west, during 1910-1911 (Clayton and Thorpe, 1982). Sulphides documented in 1954 by the Geological Survey of Canada led to staking and exploration by Texasgulf Inc. Most of the known deposits were discovered and drilled, at least to some extent, by the mid 1960's, including prospects up to 32 km east. Mineral Resources International obtained an option on the project in 1972 and ultimately commenced production in 1976.