Tungsten is a metallic element with the element symbol W and atomic number 74, which is in group VIB of the sixth period of the periodic table. Tungsten is mainly a hexavalent cation in nature, and its ionic radius is 0.68×10-10m. Due to the small ionic radius of W6+, high electric price, strong polarization ability, and easy to form complex anions, tungsten is mainly in the form of complex anion [WO4]2-, which is combined with cations such as Fe2+, Mn2+, and Ca2+ in solution to form wolframite or scheelite precipitation.
The element is a silvery-white shiny metal with high hardness, high melting point, not eroded by air at room temperature, and relatively stable chemical properties. It is mainly used to manufacture filaments and high-speed cutting alloy steel, superhard molds, and is also used in optical instruments and chemical instruments. China is the world's largest depositor of tungsten.