Temperature of crystallization of pyrrhotite and sphalerite from the Highland-Surprise Mine, Coeur d'Alene district, Idaho

The ore bodies of the Highland-Surprise Mine are replacements along shear zones in quartzose slate, quartzite, and phyllite of the Prichard Formation of the Belt series (Precambrian). Pyrite, arsenopyrite, pyrrhotite, sphalerite, chalcopyrite, and galena are the chief metallic minerals and were probably deposited in that order. Temperatures of formation were estimated for pyrrhotite-pyrite and sphalerite-pyrrhotite assemblages contained in the steeply dipping vein system. Measurements on 62 pyrrhotites indicate a range in temperature of crystallization between 370 degrees and 492 degrees C. (no correction required for confining pressures