^{Silicon Carbide
Silicon lies in the same group as carbon and, like carbon, contains four bonds. Silicon can therefore substitute for carbon in many of the carbon allotropes. In the compound silicon carbide every other carbon atom is substituted with a silicon atom so that every silicon atom is connected to four carbon atoms and every carbon atom is connected to four silicon atoms. There are two forms of silicon carbide, which are completely analogous to diamond and lonsdaleite. Gem-quality hexagonal silicon carbide is being used as a diamond subtitute and is known as Moissianite.}