A more common way of extracting tellurium from tellurides is to heat the tellurides. The tellurides are heated with sodium carbonate and air. This makes sodium tellurite. Selenites are normally found as an impurity. They are separated by reacting them with sulfuric acid. The selenites stay in solution. The tellurites turn into tellurium dioxide. Then the tellurium dioxide is reacted with sulfur dioxide dissolved in sulfuric acid to make tellurium metal. The tellurium can be melted and reformed to make bars of tellurium metal.