![]() In its raw form, tungsten is a hard steel-grey metal that is often brittle and hard to work. However, tungsten interferes with molybdenum and copper metabolism and is somewhat toxic to most forms of animal life. Tungsten is the only metal in the third transition series that is known to occur in biomolecules, being found in a few species of bacteria and archaea. Tungsten compounds are often used as industrial catalysts. Tungsten's hardness and high density make it suitable for military applications in penetrating projectiles. Tungsten occurs in many alloys, which have numerous applications, including incandescent light bulb filaments, X-ray tubes, electrodes in gas tungsten arc welding, superalloys, and radiation shielding. However, pure single-crystalline tungsten is more ductile and can be cut with a hard-steel hacksaw. Polycrystalline tungsten is an intrinsically brittle and hard material (under standard conditions, when uncombined), making it difficult to work into metal. ![]() Its density is 19.30 grams per cubic centimetre (0.697 lb/cu in), comparable with that of uranium and gold, and much higher (about 1.7 times) than that of lead. The free element is remarkable for its robustness, especially the fact that it has the highest melting point of all known elements, melting at 3,422 ☌ (6,192 ☏ 3,695 K). Its important ores include scheelite and wolframite, the latter lending the element its alternate name. It was identified as a new element in 1781 and first isolated as a metal in 1783. Tungsten is a rare metal found naturally on Earth almost exclusively as compounds with other elements. Tungsten (also called wolfram) is a chemical element with the symbol W and atomic number 74.
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