Silicon
Silicon is obtained almost exclusively by carbothermal reduction of silicon dioxide using electric arc furnaces. It is a poor conductor of heat and electricity, harder than glass, usually appears as a powder or more often as shapeless pieces of chestnut color. It crystallizes in the form of gray needles with a metallic luster.
Silicon is one of the most important materials used in electronics. Very pure silicon, obtained for example by crystal growth, can have an unprocessed elongated cylindrical or rod shape; when doped with boron, phosphorus and others, it is used for the production of, for example, diodes, transistors and other semiconductor devices, as well as solar cells.
Silicon is also used in metallurgy (for example, in iron-based or aluminum alloys) and in chemistry for the preparation of silicon compounds (for example, silicon tetrachloride).
Source: "Explanatory Notes to the Harmonized System of Goods Nomenclature for Foreign Economic Activity of the Russian Federation (HSN of Russia)" (prepared by the Federal Customs Service of Russia) (volume 1, sections I - VI, groups 1 - 29)