Te has been observed spectrographically in but a few of the more common sulphide minerals. Of these galena is probably the most important . Not seldom Te concentrations considerably higher than 10 p.p. m. are found in galena specimens. The highest Te concentrations - more than 100 p. p. m. - are here nearly always accompanied by unusually high contents of Bi and Tl. On the whole the element association Te-Bi-Pb-Tl is very characteristic in sulphidic environment.