Geologic descriptionThe Holokuk Mountain prospect consists of auriferous, sulfide-sulfosalt-bearing quartz veins in an altered porphyritic felsic intrusion with pyrite and sericite. The intrusion is associated with dark gray hornfels derived from the Upper Cretaceous, Kuskokwim Group (Cady and others, 1955). Quartz float is abundant in the area and is spread along the hill slope for about 250 feet in elevation. The prospect consists of quartz stockwork veins in an area of rubble-crop area at least 100 feet by 480 feet in size. A breccia zone in the hornfels which strikes N70W, has quartz-sulfide veins up to 4 inches thick. A north-south trending, barren mafic dike cuts both the porphyritic felsic intrusive and the hornfels with the quartz-sulfide veins. The quartz veins contain disseminations and masses of 1 to 5 percent stibnite, arsenopyrite, boulangerite?, pyrite, and kermesite. The quartz-sulfide veins comprise about 2 to 5 percent of the host rock. About 50 percent of the mineralization is in rubble-crop and talus. The mineralized zone is open-ended to the east. Twelve samples contain up to 2,700 parts per billion (ppb) gold, 35.4 parts per million (ppm) silver, 4,130 ppm arsenic, 1.06 ppm mercury, 3.0 ppm cadmium, 105 ppm bismuth, 307 ppm lead, more than 6,000 ppm antimony, 204 ppm copper, 13 ppm tin, and 12.0 ppm tungsten (T.K. Bundtzen and M.L. Miller, unpublished analytical data, 1998). |
