Australia's largest scheelite (calcium tungstate) deposit was found by Thomas Farrell in 1904, on King Island. The deposit was world class in terms of size, containing 17 million tonnes of 0.85 percent tungstate. The mineralisation is associated with granitic plutons of Devonian age.
In 1917 the King Island Scheelite Development Company installed a plant capable of treating 200 tons of ore per week. The mine closed in 1920 due to falling tungsten prices. A new company, King Island Scheelite, reopened the mine in 1937, installing a plant which could treat 500 tons of ore per week. In 1942 the commonwealth government financed the development of an open cut mine and the purchase of machinery and power shovels, as tungsten was needed for the war effort. Production increased dramatically, from 30,000 tons in 1943 to almost 130,000 tons in 1944. After the war, the demand for tungsten fell and the mine closed in 1947. Tungsten was wanted during the Korean War, and the mine reopened, but as demand fell after the war, it closed in 1958. Some limited production commenced in 1960.
During 1969 the Peko-Wallsend group of companies acquired the mine. The capacity of the mill was expanded, a port constructed at Grassy Harbour and two underground mines opened at Bold Head (1972) and the Dolphin Mine (1973), the latter extending under the sea to extract a continuation of the ore exposed in the open cut. Post-pillar cut and fill mining reduced the voids in faulted ground located beneath the sea floor. In 1984, Bold Head was shut, and continuing low prices resulted in the mine closing in 1990. The mine, which yielded 11.5 million tonnes of ore, was rehabilitated. Grassy, once a community of 750, became a tourism-based village.
Further reading: R Hooper, The King Island story, Launceston, 1973.
Carol Bacon and Wojciech Grun