2008-04-15_REVISION - M1980244 (192)

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GHMXSIopeEvaluation 2.2 Soil and Colluvium The undisturbed area was originally covered with a thin mantle (0-3 feet) of dark organic-rich loamy soil, frequently underlain by glacial colluvial materials. However the majority of the proposed mine area has been previously mined, and essentially all of the soil and Colluvium has been removed. 2.3 Mine Backfill The previous Globe Hill Mine was developed to a depth of approximately 320 feet depth, and the void created then largely backfilled with overburden material from other locations within the Cripple Creek Mine district. The backfill is made up predominantly ofend-dumped volcanic breccia and phonolite, at run-of--mine size. All of this material will be removed in the proposed mining, and none of it will form any part of the final slope of the excavation. 2.4 Bedrock The bedrock in the vicinity of the GHMX is shown in Plate 2. The bedrock comprises a weak, highly disturbed and altered pipe, surrounded by the volcanic rock suite of the Cripple Creek diatreme. These two geologic suites are greatly different geotechnically, and the mine slope design considers them separately. • 2.4.1 Volcanic Breccia and Phonolite The rock in the GHMX area lies within the Cripple Creek Diatreme, and the rocks are generally made up of volcanic phonolites, breccias, and tuff. The volcanic rocks are generally massive, moderate permeability, oxidized, jointed, with essentially random distributions of phonolite and breccia, interspersed with latite dikes and sills. The only consistent structures in these rocks appear to be sub- vertical faults and joints, oriented approximately northeast-southwest. 2.4.2 Globe Hill Pige The Globe Hill Pipe, which occupies the center and east side of the deposit. It is asemi-vertical feature containing weak, highly disturbed, highly altered rock. Much of the pipe material is disturbed to rubble, and the limited volume of intact rock encountered during drilling is anhydrite, with limited strength. 2.5 Rock Quality Rock quality is captured by the Rock Quality Designation, which is a measure of the extent to which the rock is intact. The Rock Quality Designation was computed for the core in the Globe Hill drilling programs for each core run (typically five feet long) by summing the length of core recovered in pieces longer than 4 inches (10 cm), and computing the RQD for that core run as follows: (Length of core pieces > 4") RQD = x 100% Total length of core pieces in run • Report 1385E.20071126