Tungsten General Electric's attempt to patent it, overturning granted in 1913 to William D. Coolidge. Tungsten Tungsten, or wolfram, is a chemical element with symbol W and atomic number 74. The name "tungsten" comes from the former Swedish name for the tungstate mineral "scheelite", "tung sten" or "heavy stone". Tungsten is a rare metal found naturally on Earth almost exclusively combined with other elements in chemical compounds rather than alone. It was identified as a new element in 1781 and first isolated as a metal in 1783. Its important ores include wolframite and scheelite. The free element is remarkable for its
Melting point the same space. The Lindemann criterion states that melting is expected when the vibration root mean square amplitude exceeds a threshold value. Assuming that all atoms in a crystal vibrate with the same frequency "ν", the average thermal energy can be estimated using the equipartition theorem as where "m" is the atomic mass, "ν" is the frequency, "u" is the average vibration amplitude, "k" is the Boltzmann constant, and "T" is the absolute temperature. If the threshold value of "u" is "ca" where "c" is the Lindemann constant and "a" is the atomic spacing, then the melting point is estimated