Abstract
Direct observations of the phase transformations in cubanite both on heating and cooling have been made in a transmission electron microscope. Low temperature orthorhombic cubanite undergoes a cation disordering process at about 200° C resulting in a hexagonal wurtzite type structure. The reordering process takes place by the growth of independently nucleated regions of short range order. Long range order is difficult to attain in short term experiments due to the lack of order correlation between regions. At a slightly higher temperature a transformation from hexagonal close-packing to cubic close-packing takes place within the sulphur structure, by the propagation of partial dislocations along alternate close-packing planes. This transformation is irreversible. On cooling the disordered cubic structure, cation ordering takes place as an alternative to the transformation back to hexagonal close-packing, but in the absence of an ordering scheme at this composition based on the cubic subcell, the ordering process results in the exsolution of chalcopyrite. This transformation is interpreted in terms of metastable, kinetically controlled behaviour.
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References
Bollmann, W.: Crystal defects and crystalline interfaces. Berlin Heidelberg New York: Springer 1970
Buerger, M.J.: The crystal structure of cubanite. Am. Mineral 32, 415–425 (1947)
Cabri, L.J.: New data on phase relations in the Cu-Fe-S system. Econ. Geol. 68, 443–454 (1973)
Cabri, L.J., Hall, S.R., Szymanski, J.T., Stewart, J.M.: On the transformation of cubanite. Can. Mineral. 12, 33–38 (1973)
Dutrizac, J.E.: Reactions in cubanite and chalcopyrite. Can. Mineral. 14, 172–181 (1976)
Fleet, M.E.: Refinement of the crystal structure of cubanite and polymorphism of CuFe2S3. Z. Kristallogr. 132, 276–287 (1970)
Hall, S.R.: Crystal structures in the chalcopyrite Series. Can. Mineralogist 13, 168–172 (1975)
McConnell, J.D.C.: Analysis of time-temperature-transformation behaviour of the plagioclase feldspars. In: Proceedings of the NATO Advanced Study Institute. McKenzie, W.S., Zussman, J., Eds., pp. 460–477. Manchester: University Press 1974
Putnis, A.: Observations on coexisting pyrrhotite phases by transmission electron microscopy. Contrib. Mineral. Petrol. 52, 307–313 (1975)
Putnis, A.: Observations of transformation behaviour in Ni7S6 by transmission electron microscopy. Am. Mineral. 61, 322–325 (1976a)
Putnis, A.: Alternative transformation behaviour in sulfides: direct observations by transmission electron microscopy. Science 193, 417–418 (1976b)
Putnis, A., McConnell, J.D.C.: The transformation behaviour of metal enriched chalcopyrite. Contrib. Mineral. Petrol. 58, 127–136 (1976)
Szymanski, J.T.: A refinement of the structure of cubanite CuFe2S3. Z. Kristallogr. 140, 218–239 (1974a)
Szymanski, J.T.: The crystal structure of high temperature CuFe2S3. Z. Kristallogr. 140, 240–248 (1974b)
Vaasjoki, O.: On the striation developed in cubanite by heating, a criterion for thermometamorphism. Mineral. Deposita 6, 103–110 (1971)
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Putnis, A. Electron microscope study of phase transformations in cubanite. Phys Chem Minerals 1, 335–349 (1977). https://doi.org/10.1007/BF00308844
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DOI: https://doi.org/10.1007/BF00308844