Fig. 1. Location of Precambrian Gold Butte area, Nevada, and geologic map of Gold Butte anticline. Mine symbol locates vermiculite mine. Grid pattern from Gold Butte 7 1/2 Minute Quadrangle, Nevada, is 1 km on a side. Symbols A-F refer to units in Fig. 2. Sites a, b, and c (outlined in red boxes) are illustration locations on Fig. 4. Garnet gneiss includes gneisses that may also contain sillimanite +/- cordierite. Symbol for dark mafic rocks (paired-line patterns) include mafic diorite, gabbro, mafic gabbro, and pyroxenites that have abundant mafic silicates. Twenty analyzed rocks are approximately located by sample numbers, but tables of analyses have been omitted from this web site.