A polymer in which the main chain contains no carbon atoms and in which behavior similar to that of an organic polymer can be developed, i.e., covalent bonding and cross-linking, as in silicone polymers. Here the element silicon replaces carbon in the straight chain; substituent groups are often present, forming highly useful polymers. Other inorganic high polymers are black phosphorus, boron, and sulfur, all of which can form polymeric structures under special conditions. At present these have little or no commercial significance.Note: Some authorities consider silicone resins to be semiorganic, since their substituent groups are composed of methyl groups.