Silicon. Sample of crude-refined silicon. Silicon is a semiconductor group IV metal, with atomic number 14. It is not found as a native element, but is the second most abundant element in the Earth's crust, occurring as silica (silicon dioxide). Crude silicon may be obtained by reducing silica with carbon in a furnace. Pure silicon is obtained by conversion to silicon tetrachloride, then reduction on a hot wire and zone refining. Exceptionally pure silicon is used as the substrate for electronic devices. Its diamond-type lattice structure means that it may be 'doped' with electron donors or acceptors to form transistors and diodes.