THE TL-FE-S SYSTEM - DRY EXPERIMENTS AT LOW-TEMPERATURES

The Tl-Fe-S ternary system, which directly concerns the two rare miner als raguinite (TlFeS2) and picotpaulite (TlFe2S3) in the Allchar depos it, was subject of a systematic study under dry conditions at 180-300 degrees C. Nine ternary phases or solid solutions, including the two c ited above, have been concretely established. All of which persist bey ond 300 degrees C. The determined formulas are Tl2FeS3-Tl5Fe3S7 s.s. s eries, TlFeS2, TlFe2S3, (Tl,Fe)(3)S-2 s.s., Tl5FeS4, Tl4Fe2S5, Tl3Fe2S 4, Tl3Fe4S6 and Tl2Fe2+xS3+x s.s. series. Two additional Tl-rich phase s were detected with coexisting liquid, but their exact compositions c ould not be located. The experiments led further to the construction o f three isotherms at 220, 260 and 300 degrees C. The 180 degrees C iso therm remains incomplete. The experimentally established assemblage Tl FeS2-TlFe2S3-FeS2 agrees with the paragenesis observed in natural envi ronments.