Tungsten is used to make things that must withstand intense heat. In 2007, 54,600 metric tonnes of tungsten were mined all over the world.
Physical properties: Tungsten is a very hard (7.5 on a 10 point scale), very dense (19.25 gram/cm3) and heavy steel-gray metal. It is brittle and hard to mould and shape except in its very pure state. Tungsten has the highest melting point of all metals, 3422C, and molten tungsten boils at 5555C. Tungsten mixes with iron, nickel and cobalt to produce hard and heavy alloys.
The word "tungsten" comes from the Swedish words "tung" and "sten", which together mean "heavy stone", referring to the high density of the metal.
Chemical properties: Tungsten is not a reactive metal. Acids, alkalis and oxygen have no effect on tungsten. This makes it suitable for uses like jewelry and other durable objects. Tungsten does combine with carbon to produce tungsten carbide, a very hard material that is used to make machine tools (that cut or drill metal) and armor-piercing ammunition.
History: In 1781, Carl Wilhelm Scheele (1742-1786) found that a new acid, tungstic acid, could be produced from the ore scheelite. Scheele and Torbern Bergman (1735-1784), a Swedish chemist, suggested that this acid might contain a new element, though they could not extract it. In 1783, the Spanish brothers José (1754-1796) and Fausto Elhuyar (1755-1833) reacted the acid with charcoal, and managed to isolate tungsten. They are now recognized as having discovered tungsten. Because of its high melting point, and the strength it brought to alloys, tungsten found ready use in making weaponry in World War II. Portugal, the main producer at that time, was pressured by both sides to supply the metal.
Production: Tungsten is found in the ores wolframite, scheelite, ferberite and hübnerite. The ores are converted to tungsten oxide, which is then reduced (i.e. has the oxygen removed) using carbon or hydrogen, to produce powdered tungsten. The top producers of tungsten are China, Russia, Canada, Austria, and Bolivia. Pie Chart of Top 5 Tungsten Producing Countries...
Uses: Because of its high melting point, tungsten is used in light bulbs, heating elements, rocket engines, and welding equipment. Its hardness and density finds use in making weights and ballast for yachts, racing cars, and aircraft. Tungsten placed at the tip of fishing hooks make them heavier and sink faster. The tips of darts are also tipped with tungsten to help them fly straight. Tungsten is used by the military to make cannon shells, grenades, and missiles. Finally, tungsten can also be used to make jewelry with a distinctive brushed finish. Tungsten jewelry does not scratch easily, and does not need polishing, so it lasts a long time.
Health: Some studies show that people with leukemia have higher levels of tungsten in their bodies. Tungsten has come under suspicion for causing the disease, but no conclusions have been drawn yet. In the soil, tungsten acts as a substitute for molybdenum in enzymes and other biological materials.
Turrell, Kery. Tungsten : The Elements, 2003, Marshall Cavendish, USA.
Tungsten, Wikipedia. <http://en.wikipedia.org/wiki/Tungsten> accessed on 18-Feb-2009.
Tungsten, Mineral Information Institute. <http://www.mii.org/Minerals/phototung.html> accessed on 20-March-2009.
Uses, International Tungsten Industry Association. <http://www.itia.org.uk/Default.asp?page=34> accessed on 20-March-2009.