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• Geology of the East Cresson Mine Area is similar to that of the Main Cresson <br />Mine Area with the exception that there are volumetrically more phonoli[es than <br />diatremal breccias and Precambrian granites are mineralized in [he northwest portion of <br />the mine. The East Cresson Mine is focused on the intersection of the Pharmacist Vein <br />and the Isabella-Buena Vista vein systems, in the area of the former "Gold Star Mine". <br />Diatremal breccias lie between thick phonolite sills and are cut by later phonolite and <br />lamprohyre dikes. The floor of the East Cresson Mine is dominantly phonolite. <br />In the northwestern portion of the mine, vein systems cut through the contact <br />between the the volcanic rocks in the diatreme and a pendant of highly oxidized <br />Precambrian granodiorite. Structural trends are dominantly I~1NW and are cut by <br />subordinate NE trends. <br />The Globe Hill-Ironclad area, where mining occurred into 1944 and where the <br />surface mines have been and are being backfilled, is dominated by diatremal breccia and <br />• phonolitic country rock that was intruded by a series of late stage breccia pipes. These <br />breccia pipes hosted most of the gold mineralization in the area and are characterized by <br />strong zoned argillic alteration. The breccia pipe bodies are generally less than 500 feet <br />in diameter and occur at the intersection ofnortheast- and north-northwest-trending <br />structural zones. <br />The western part of the Globe Hill-Ironclad area and the SGOSA is dominated by <br />a large northwest-trending, elongate Precambrian schist body surrounded by diatremal <br />breccia (Cripple Creek Breccia). Both the schist and breccia aze oxidized on the surface <br />with zoned weak argillic alteration. This area has been intruded by scattered and <br />discontinuous lamprophyrie and phonolitic dikes as well as a small plug of porphyritic <br />phonolite. This contact is steep and only shows weak argillic alteration. The dominant <br />structural trends in this area are similar to the rest of the area with north-northwest- and <br />northeast-trending fabric. <br />u <br />17 <br />