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Show 58 Fischer in his suggestions for prospecting states; "Because of the extreme spottiness of ore bodies and the large ratio of barren to mineralized ground....wildcat drilling, at some distance from known ore bodies, should be largely restricted to established alinements. Wildcat drilling across the recognized alinement in Long Park, Montrose County, Colo., has disclosed several ore bodies more than a thousand feet from ground previously known to be mineralized." Mining thus far has been confined largely to tunnels driven into the sandstone from the outcrop (see pi. 9). A typical example of such tunnels is shown in plate 10. Important ore bodies occur beneath the surface of the benches that form at the top of the ore-bearing., horizon. Plate 11 shows an excavation made with bulldozer and power shovel in the removal of ore at the surface of a bench from the Gramlich group in the West Paradox area; plate 12 shows a similar mine in the Maverick group in the Gateway area. The ore discovered In Long Park referred to in Fischer's quotation is an example of ore at a shallow depth below the surface of a bench but too deep for open-cut methods and hence where shafts must be used. Plate 13 shows an area of shaft mining on the Snyder-Dunning and Spud Patch groups in the Slickrock area. The ore reserves of Southwestern Colorado can only be estimated because mine development and exploratory diamond drilling have not been kept far ahead of actual mining. The larger companies seldom develop an ore reserve of more |
