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W�!'"ITASCK <br /> Denver, Inc. <br /> 2.2 UPDATED ROCK-TYPE GROUPS <br /> The rock-type classification scheme used by CC&V was slightly revised while Phase II testing was <br /> underway. The revised rock-type groups and their approximate relative abundances in Project <br /> waste rock are listed as follows: <br /> 1. Generic Precambrian (1%), <br /> 2. Biotite schist/gneiss (4%), <br /> 3. Dump/fill material (10%)1, <br /> 4. Cripple Creek breccia (54%), <br /> 5. Aphanitic phonolite (<1%), <br /> 6. Lamprophyre (1%), <br /> 7. Hydrothermal breccia (2%), <br /> 8. Porphyritic phonolite (1%), <br /> 9. Phonolite breccia (26%), and <br /> 10. Syenite (1%). <br /> The LE COW database samples were categorized into updated rock-type groups based on their <br /> rock type, as indicated in Table 2-2. However, it is not certain that the rock types directly map to <br /> the updated rock-type groups, and the updated rock-type group designations for the LECOTM <br /> database samples are based on limited information (geologic logging under historical rock-type <br /> classification schemes). For this analysis, the various quartz vein rock types were grouped with <br /> syenite because they are all intrusive igneous rock, though there are notable differences in <br /> composition. Figure 2-3b shows the approximate distribution of NNP values for each updated <br /> rock-type group. As illustrated in Figure 2-3 and Appendix A, the distribution of acid-generating <br /> characteristics is similar across rock-type groups and geologic classifications, so the updated rock- <br /> type groups do not have distributions that vary meaningfully from the previous rock-type groups. <br /> However,the updated rock-type groups do subdivide the large breccia and porphyritic phonolite <br /> 1 Dump/fill material was not characterized because it is assumed to be composed of the other rock-type groups. <br /> 6 <br />