Crystalline silicon steel gray, amorphous silicon is black, density 2.4g/cm3, 1420 c melting point, boiling point 2,355, belongs to the Atomic crystalline silicon crystals, hard and shiny, with semiconductor properties. Property comparison of silica and lively, at high temperatures can combine with oxygen and other elements, does not dissolve in water, nitric acid and hydrochloric acid, solution, hydrofluoric acid and lye, used in making alloys such as ferrosilicon, silicon steel, Silicon is an important semiconductor material, used in the manufacture of high-power transistors, Rectifier, solar cells, and so on. Silicon are very widespread in nature, in the Earth's crust contains about 27.6%, mainly silica and silicate crystalline silicon is in the form of dark blue, very crisp, is typical of semiconductors. Property is very stable. At room temperature, except for hydrogen fluoride, it's hard to react with other substances.