Natural tellurium occurs in small amounts and is fairly widespread in complex gold, silver, lead, antimony, bismuth and copper compounds. Tellurium is a metalloid very similar to selenium and like all metalloids has non-metallic characteristics, including poor heat and electrical conductivity. It has few uses in the pure state and there is no alloy system based on tellurium. Some use has been made of the material in the vapour form in lamps when it is claimed artificial sunlight can be obtained. In the finely divided form tellurium is used as an additive to rubber to improve the oxidation resistance.