Relationship between low-grade gold disseminations and high-grade veins in the Quartz Mountain district,Oregon

Gold and mercury mineralization related to epithermal hot springs occurs spatially associated with rhyolite dome complexes in the Quartz Mountain district, Lake County, Oregon. Drilling of over 800 holes from 1983 to 1991, mostly by Quartz Mountain Gold Corp., has resulted in a mineral inventory of at least 100,000,000 tons, averaging 0.0255 ounce gold per ton in two near-surface, disseminated gold ore bodies, Quartz Butte and Crone Hill. Extensive gold disseminations are underlain by and include rare, higher-grade veins that could be feeders for the near-surface, quasi-horizontal, pervasively mineralized gold dissemination. The veins contain about 2,000,000 tons of ore, aver-aging 0.29 ounce gold per ton. Approximately 750,000 tons of this underlie Quartz Butte, and the remainder is included in the Crone Hill low-grade dissemination. With a mineral inventory of about 3,000,000 ounces, Quartz Mountain is currently the largest known gold deposit in Oregon.As now known, the veins seem too few in number and too sporadically positioned to account for the volume of near-surface gold disseminations. We offer hypotheses to explain the apparent anomaly between the volume of disseminated gold ore and the paucity of feeders. Quartz Mountain has numerous alteration and mineralization similarities with the well-studied Steamboat Springs district (White and others, 1964). Coincidences between the two districts are noted.