Quiz: Remember the definition of mal de mer?
calcium tungstate mineral, CaWO4, that is an important ore of tungsten. It acquired commercial value in the 20th century when tungsten became used in alloy steels and electric-light filaments. The mineral is named in honour of the Swedish chemist Carl Wilhelm Scheele, who obtained tungstic acid from it in 1781. Scheelite commonly occurs as compact or granular masses in contact metasomatic deposits, high-temperature veins, and granite pegmatites. In the United States it has been mined extensively in North Carolina, California, and Nevada. It also occurs in Cornwall and Cumberland in England, and in Bolivia, New South Wales, New Zealand, Siberia, Switzerland, and France.