Geology topics
Research about Shoshone County, Idaho
Source-linked reports with geographic coverage including Shoshone County, Idaho.
Geology of the Coeur d'Alene district, Shoshone County, Idaho
The Coeur d'Alene district, near the base of the northern panhandle of Idaho, is one of the world's larger lead- zinc and silver-producing areas. The greater part of the dis~rict i~ included within five map areas, from east to west the Pottsville, Mullan, Wallace, Kellogg, and Smelterville, which were geologically mapped during this study. These quadrangles encompass an area about 26 miles long in an east-west direction and about 9 miles wide. The district lies wholly within the Coeur d'Alene Mountains, the part of the Bitterroot Range that is drained by the Coeur d'Alene River. The Bitterroot Range is a rugged, deeply dissected mountain mass which extends on both sides of the Idaho-Montana boundary for more than 200 miles and is a part of the Northern Rocky Mountains; within the district the range has a relief of 3,000-4,000 feet. The westward-flowing South Fork of the Coeur d'Alene River bisects the district, and roads along this river and its major tributaries generally provide easy access to the communities and many mines.
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 <2000 bars below 670 degrees C.), and measurements on 14 sphalerites indicate crystallization temperatures between 375 degrees and 460 degrees C. (uncorrected for confining pressure). No systematic temperature gradients were recognized. Minor elements in 23 pyrrhotite, 8 pyrite, 13 sphalerite, and 2 galena samples were determined. Partition ratios of Ni and Co in pyrrhotite-pyrite and sphalerite-pyrrhotite pairs are erratic. This suggests a dis-equilibrium distribution of these elements between the phases of each mineral pair and/or b) crystallization of the mineral pairs under different physical conditions.
Geochemical studies in the Coeur d'Alene district, Shoshone County, Idaho
No abstract available.