What is tungsten? Tungsten, meaning “heavy stone” in Swedish, is a very hard and heavy silver gray rare metal. With the highest melting point among metals, tungsten has a relatively large electric resistance as a metal, so it is used for heaters and reflectors in furnaces exceeding 2000?. It also becomes a hard alloy when mixed with carbon, etc. Cemented carbide combined with cobalt is used for high-grade cutting tools. In addition, tungsten, with extremely low environmental impact, has a very high radiation shielding capability compared to lead; it is also widely used as radiation shielding material in medical field such as X-ray CT. Tungsten does not seem familiar to us in our daily life, but it is closely related to our lives for its industrial and medical uses.