Great article from IEEE about the brewing controvery over China's export policies on rare earth metals (think magnets), tungsten (think semi-conductors), and molybdenum (think stainless steel, water & food & hospital distribution systems).
Effected industries include automobile manufacturing, electronics (including semi-conductors), oil & gas production, medical equipment, and more.
China has the largest Tungsten reserve. A distant second is Russia, followed by Canada and the U.S. The last time the US produced Tungsten was in 1994. The last time the US processed Tungsten concentrates was in 2004*.
Tungsten is used extensively in making cemented carbide parts (cutting and wear-resistant materials for metalworking, oil & gas production, construction). It can also be found in lamp filaments, electrodes, electrical and electronic components, tools, alloying metals, chemical catalysts, and pigments.
Of course, the world is busy working on alternative materials and sources. Time will tell.
*Source: U.S. Geological Survey, Mineral Commodity Summaries, January 1998