Germanium is not very abundant, so that we can even say that it is a rare element. Its principal compounds are argyridite (4Ag2S.GeS2), germanite (7CuS.FeS.GeS2), canfieldite (4Ag2S.(Sn,Ge)S2) and renierite ((Cu, Ge, Fe, Zn, As)S). Of these only the germanite deposits in Tsumeb (Southwest Africa) and renierite deposits in Katanga (Congo) are of major industrial significance. Trace amounts of germanium (up to 0.3%) are reported in many sulfide and oxide minerals and coal.