Abstract

The temperature and pressure during vein deposition at the McIntyre Mine were determined using electrical measurements of pyrite and the decrepitation temperature of quartz, pyrite, ankerite, and calcite. It was concluded that there were two separate stages of mineralization, the first extending over the range of 630 degrees to 400 degrees C at a depth of 10 kilometers, and the second at 150 degrees C and at a much shallower depth. Variations of temperature of deposition of pyrite were found to be unrelated to depth in the mine and to individual veins, but were found to be related to the distance from the contact of the porphyry and the wall rock. A gradient of the mean temperature of deposition was found to be 14 degrees C per 100 feet, from 500 feet within the porphyry to 500 feet outside the porphyry. The mineralization and the porphyry intrusives are closely related in space, time of emplacement and probably also in origin.

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