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�f ITASCAM <br /> Denver, Inc. <br /> of pyrite,with potential additional minor contributions from the acid-sulfate minerals alunite and <br /> jarosite. The highest measured ANP values correspond to samples that contain carbonate <br /> minerals. <br /> 3.4 SOLID-PHASE CHEMICAL COMPOSITION <br /> Solid-phase chemical composition testing was conducted on each of the 12 Phase II samples to <br /> identify the concentrations of elements that may become mobile in the environment. <br /> 3.4.1 Methods <br /> Solid-phase rock composition was determined using the acid-digestion method described in US <br /> Environmental Protection Agency method 3050E (USEPA 1996). Samples were digested with <br /> repeated additions of nitric acid and hydrogen peroxide. The digestate was then analyzed by <br /> ICP-AES and ICP-MS to measure the solid-phase elemental concentrations of select metals, <br /> metalloids, and nonmetals. <br /> Acid-digestion method 3050B is a strong acid digestion that will dissolve almost all elements that <br /> could become environmentally available; it is not a total digestion. The method is designed such <br /> that elements strongly bound in primary silicate structures are not normally dissolved by this <br /> procedure, as they are not usually mobile in the environment (USEPA 1996). <br /> 3.4.2 Results <br /> The results of the solid-phase testing are listed in Table 3-4, and the original data sheets from the <br /> laboratory analysis are provided in Appendix B. It is important to note that the solid-phase <br /> concentrations are unlikely to occur under field conditions because any release of the <br /> constituents would occur over a long period of time, and the samples will not dissolve nearly as <br /> completely under environmental conditions as in the laboratory acid-digestion procedure. <br /> 21 <br />