Period 6 element niobium, occurs in the minerals tantalite, columbite and coltan (a mix of columbite and tantalite). Tungsten, also known as wolfram, is a chemical element with the chemical symbol W and atomic number 74. The word "tungsten" comes from the Swedish language "tung sten" directly translatable to "heavy stone", though the name is "volfram" in Swedish to distinguish it from Scheelite, in Swedish alternatively named "tungsten". A hard, rare metal under standard conditions when uncombined, tungsten is found naturally on Earth only in chemical compounds. It was identified as a new element in 1781, and first isolated as a metal in
Melting-point apparatus range to be recorded. A Thiele tube is a glass instrument that is filled with oil that is heated by using an open flame. The sample is placed in the opening in a capillary tube alongside a mercury thermometer and allowed to be heated by the oil as it circulates through the Thiele tube. By using different oils, different temperature ranges can be reached and used to determine melting points. The Thiele tube may also be used to determine boiling points, by using a liquid sample instead of a solid sample. Melting-point apparatus A melting-point apparatus is a scientific instrument