Germanium occurs in nature in the form of argyrodite, a sulfide of silver and germanium, coal, germanite, and zinc ores. Commercial isolation of germanium occurs generally from zinc ore smelter dust processing and from the combustion of byproducts from certain types of coals. The combustion process uses exothermic chemical reactions along with heat and light.
There are two processes that can be used to further isolate germanium: treatment with hydrogen, and treatment with carbon. The germanium oxide, GeO2, can be reacted on a one to two basis with carbon, or hydrogen, to produce pure germanium and carbon monoxide or water.
Very pure germanium can also be isolated by treating germanium chloride with hydrogen; this reaction yields pure germanium and hydrochloride; this process uses fractional distillation and the highly reactive and volatile germanium tetrachloride. Fractional distillation uses the different volatile properties of germanium contaminants to yield the high quality amounts of fractional distillation. These isolation procedures are usually not carried out on a small scale laboratory basis.
