Geologic descriptionThis occurrence was first described by Roehm (1942) and was recently mapped and sampled by Still and others (2002). The deposit consists of several quartz veins with an aggregate thickness of about 6 feet. The veins are associated with a fault zone and are generally parallel to the bedding of the folded host rocks, which are limestone, silty limestone, and chert. The rocks are part of the Bay of Pillars Formation of Silurian age (Brew and others, 1984). A large Cretaceous hornblende quartz monzonite crops out about a mile to the east. The veins, fault zone, and strata generally strike N60W and dip 75 SW to vertical. The veins contain irregular masses, bands, and disseminations of pyrite with minor sphalerite and galena. The highest grade sample collected by Still and others (2002) across 1.3 feet of a quartz vein contained 134 parts per billion gold, 2,959 parts per million (ppm) zinc, and 1,264 ppm arsenic. Another sample contained 15 ppm silver and 353 ppm lead across 0.7 feet and a sulfide-rich sample collected in the quartz vein contained 25.2 ppm silver, 1,153 ppm copper, 8,692 ppm lead and 14,558 ppm zinc. |
