The melting point of tungsten is the highest among all metallic elements, and its density (19.3 g / cm³) is very high, close to gold. The hardness of tungsten is also very high, and the hardness of tungsten carbide is close to that of the diamond. In addition, tungsten has good electrical conductivity, resonance, small expansion coefficient, and other characteristics, so it is widely used in the industry and our daily life. The present book deals with the history, properties, uses and application of metalloenzymes.