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<br />'Hl' !;., ') <br />VJ;"UV <br /> <br />The Ruby and Elk Mining Districts have produced significant quantities <br />of lead, zinc, silver, and gold ore since the 1870's. The Study Area <br />is located on the north side of the Ruby District. Silver ore in the <br />Ruby District is found in fault fissures associated with igneous <br />intrusions. The most successful mine in the Ruby District was the <br />Forest Queen Mine which produced over $1,000,000 in silver from 1879- <br />1900. Several producing mines in the Elk district also lie near the <br />Study Area, including the Keystone which produced $20,000,000 worth of <br />lead, zinc, copper, and silver from 1955-1976. These productive mines <br />are outside the Study Area but are located on a system of mineralized <br />faults which extend into the Study Area in Peeler Basin. <br /> <br />The Study Area has the same formations and structural features as the <br />producing parts of the Ruby and Elk Mining Districts. An extensive <br />system of faults and dikes related to the igneous intrusions covers <br />the western one third of the Study Area and parts of Peeler Basin. <br />The faults are commonly mineralized with base and precious metal <br />bearing minerals. The Study Area has a thick sequence of Mesaverde <br />Formation sandstones which were the main ore producing units in the <br />Forest Queen and Keystone mines. <br /> <br />No commercial molybdenum ore has been produced from this part of the <br />Colorado Mineral Belt closer than the Climax Mine, northeast of Leadville. <br />Tile Study Area, however, lies within one mile of the recently discovered <br />Mt. Emmons ore body. This ore body contains an estimated 155,0(:),000 <br />tons of 0.43% molybdenum disulfide. AMAX has proposed a 20,000 ton <br />per day mine which is currently being evaluated by the Forest SErvice <br />and other agencies. The Mt. Emmons ore body is spatially and genetically <br />related to the buried Oh-Be-Joyful granitic intrusive. <br /> <br />The Redwell Basin breccia pipe complex also lies less than one mile <br />from the Study Area. About 2,000 feet below the base metal zones are <br />two zones of high tungsten, tin, and molybdenum values. The lower <br />zones are related to the Redwell Basin granite intrusive and are <br />similar geologically to the Climax and Henderson molybdenum deposits. <br /> <br />The Mt. Emmons and Redwell Basin intrusives are younger in age and <br />more felsic in composition than the intrusi'Jes comprising the Ruby <br />Range. These younger granite intrusives ha'/e been dated at 12 to 17 <br />million years, whereas the Ruby Range granodiorites are dated at 29 to <br />34 million years. Molybdenum mineralization appears to be primarily <br />associated with the younger intrusives whil(~ other base1i?d precious <br />metals are associated with both groups of illtrusives. -- There are <br />other younger granite intrusives in the regJon. Treasure Mountain. <br />twelve miles to the northwest of the Study l.rea, is a large granitp <br /> <br />10/ <br /> <br />_1_0/ Sharp, J.E., 1976, A Molybdenum r'1ineralized Breccia Pipe, Redwell Basin, <br />Colorado, Economic Geology, Vol. 73, p. 369-382. <br /> <br />11/ <br /> <br />Dowsett, F.R., Ganster, M.W., Ranta, D.E. Baker, D.J., and Stein, {.J., <br />1981, Geology of the Mount Emmons molybdenum deopoit, Crested Butt(~, <br />Colorado, unpublished manuscript, p. 2-3. <br /> <br />34 <br />