Microprobe analyses of ore samples suggest equilibrium on the microscale of individual polished sections. Sphalerite with pyrite and pyrrhotite ranged from 8.9 to 13.3 mole percent FeS, with pronounced mode at 11-12 percent. Sphalerite with pyrite alone had larger range of 2.7-13.7 percent and same mode. This modal composition is in better accord with Barton and Toulmin's (1966) extrapolation of the curve for the composition of sphalerite in equilibrium with pyrite-pyrrhotite than with the experimental results of others.

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