Geologic descriptionThe rocks in the vicinity of this occurrence are interlayered Paleozoic amphibolite-facies paragneiss, schist, amphibolite, orthogneiss, and minor marble that have been intruded by small Jurassic plutons and dikes (Werdon and others, 2001). The Jurassic igneous rocks are generally white, fine-grained, aplitic- to graphic-textured granite dikes, but they transition westward into a tan, fine- to medium-grained, equigranular, biotite granite. Both the white and tan granites are cut by stockwork milky, quartz veins. Most quartz veins do not contain visible sulfides, but many of the white granites contain as much as 2 percent disseminated limonite (pseudomorphs after pyrite?). Calc-silicate skarn float is present above the intrusions; it contains pyrrhotite, pyrite, and an unknown silver-gray mineral (hematite or molybdenite?); ore samples contain 120 ppm tungsten. An iron-stained, color-banded quartzite (or former quartzose gneiss?) with pyrite(?) or pyrrhotite along fracture surfaces contains 45 ppm molybdenum and 212 ppm zinc; a quartzite or hornfels with iron-sulfides and unknown silver-gray mineral contains 26 ppm molybdenum, 276 ppm lead, and 550 ppm zinc (Werdon and others, 2000). |
