Phase relations in the systems PbS-Sb 2 S 3 -Bi 2 S 3 and PbS-FeS-Sb 2 S 3 -Bi 2 S 3 were studied using evacuated capsule technique, X-ray powder diffraction, reflected light microscopy, and electron microprobe analysis. Seven new phases found in the systems are designated as phases C, K-K Fe , X, Y-Y Fe , Z, W, and R for convenience in their descriptions. Phases C, K-K Fe , and R have compositions and crystal structures comparable to cosalite, kobellite, and bismuthian robinsonite, respectively. Others have no distinct natural counterparts.The cosalite-like phase (C) when synthesized has a composition of 2PbS.(Bi (sub 0.80) Sb (sub 0.20) ) 2 S 3 and is stable to 715 degrees + or - 5 degrees C. No Sb-free cosalite was observed in the system. Kobellite, on the other hand, was synthesized from a series of compositions from 6PbS.FeS.Sb 2 S 3 .2Bi 2 S 3 (K Fe ) to 3PbS.Sb 2 S 3 .Bi 2 S 3 (K).Phase X, 9PbS.11 (Bi (sub 0.64) Sb (sub 0.36) ) 2 S 3 , is the only ternary phase synthesized in the PbS-poor half of the system PbS-Sb 2 S 3 -Bi 2 S 3 . Phase Y ranges in compositions from 2PbS.(Sb (sub 0.50) Bi (sub 0.50) ) 2 S 3 (Y 1 ) to 2PbS.(Sb (sub 0.76) Bi (sub 0.24) ) 2 S 3 (Y 2 ). The Sb-rich end members form equilibrium assemblages with sulfantimonides, whereas the Bi-rich end members form equilibrium assemblages with sulfbismuthinides. Members of intermediate compositions exist in equilibrium with galena. Phase Z, a low-temperature form of phase Y, is stable below 407 degrees + or - 8 degrees C.Phase W has a composition of 3PbS.(Sb (sub 0.80) Bi (sub 0.20) ) 2 S 3 and exists in a very limited association with other phases in the system PbS-Sb 2 S 3 -Bi 2 S 3 . Phase R has a composition of PbS.(Sb (sub 0.50) Bi (sub 0.50) ) 2 S 3 and a range of solid solution toward robinsonite.The system PbS-FeS-Sb 2 S 3 -Bi 2 S 3 is characterized by the formation of a single-phase plane defined by Y Fe , 6PbS.FeS.2Sb 2 S 3 .Bi 2 S 3 , Y 1 , 2PbS.(Sb (sub 0.50) Bi (sub 0.50) ) 2 S 3 , and Y 2 , 2PbS.(Sb (sub 0.76) Bi (sub 0.24) ) 2 S 3 . In the region between 66.66 and 60.00 mole percent PbS, stable binary assemblages consisting of (K-K Fe ) and (Y-Y Fe ) solid solutions are: K Fe -K-Y 1 , K Fe -K-Y Fe , K Fe -K-C, K Fe -K-lillianite solid solution, Y 1 -Y Fe -K, Y 1 -Y Fe -K Fe , Y 1 -Y 2 -K, Y 2 -Y Fe -K, Y Fe -Y 2 -boulangerite, and Y 2 -Y Fe -2PbS.Sb 2 S 3 .

This content is PDF only. Please click on the PDF icon to access.

First Page Preview

First page PDF preview
You do not have access to this content, please speak to your institutional administrator if you feel you should have access.