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bottom area collected during three sampling events in April,October and December 1996. The samples were collected from a boat or from the frozen pond surface with a W ildco dredge sampler. e� Solids and=ompanying water were placed in five gallon buckets and transported to the lab for analysis. All analytical work was performed at the facilities of ACZ laboratories, Inc. in Steamboat Springs,CO. -i".•• Determination of percent solids was not performed since the method of sample collection made this analysis somewhat arbitrary. Samples were air dried prior to analysis for total metals. Samples were digested by microwave techniques in nitric acid and_Ihen analyzed by inductively '(. .' coupled plasma spectroscopy(ICP,EPA M6010). Aluminum,calcium,iron,manganese and zinc were determined in this manner. X-ray diffraction(XRD)analysis was performed on all samples by R.Corbett at the Cyprus Miami mineralogical facility,Claypool,AZ. Small representative splits of each sample were pulverized by hand with an agate mortar and pestle to provide minus 270-mesh material for analysis. Powders were packed in bulk sample holders and were scanned over the range 20=3- .. / / 75' with CuKa radiation. Tha resulting XRD patterns were interpreted by a combination of • computer and manual methods. Relative peak intensities were used to make semi-quantitative �,. abundance estimates. The lower limit of the XRD technique to resolve trace mineral phases is approximately J percent. The technique is unable to distinguish poorly crystalline or amorphous phases. ,� r .S Electron microscopy was performed by D.R.Brosnahan at the Barrick Goldstrike Mine facility j near Elko,NV using a JEOL 733 wavelength dispersive microprobe. Accelerating voltage was 25kV,sample current was JOnA and beam diameter was I km. Additional XRD scans were also performed at these facilities. •, „�- ggtt�=i, 4 CHARACTERIZATION OF SLUDGE SAMPLES The chemical,mineralogical and textural characteristics of the four samples were determined by various analytical techniques. These characteristics are important variables, and aid in the f interpretation of the leaching data,which is discussed in the companion paper. \ 4.1 Mnemlogical composition by XRD d The mineralogical composition of the sludge samples,as determined by XRD,is summarized in i� 9 Table I and Figures 3 and 4(Corbett 1997;Brosnehan 1997). Samples fall into two types;those dominated by a detrital component from the underlying failings(samples from 3-dam and 5-dam) • and those dominated water treatment products(samples from the delta and 6-riser). The two 7 p samples with large derital components we primarily composed of quartz and muscovite,with minor potassium feldspar (orthoclase), albite and calcite, with trace kaolinite, gypsum and !1`. "( 6 r. Q1 ' molybdenite. These samples contain a small sludge component, reflected by the presence of i 1 ;a t: • gypsum and calcite, since these minerals are uncommon in the Climax orebody. The total p unidentified portion of these sam les was estimated at 3-10 percent. The low background counts on these scans indicate there is little amorphous material. Samples with a large sludge component are dominated by the hydrated calcium-aluminum Q Q Q ) sulfate hydroxide mineral ettringile(Cat lr(SOr),(OH)jr•26HtO),with minor calcite,fluorite,and Irace to minor quartz. Calcite appears to be more abundant in the 6-riser sample. The total unidentified component was estimated at 3-10 percent. Higher background and broad peaks in the 6-riser and delta sears indicate that at least some of the sample is corn p posed of amorphous or poorly crystalline material. Figure 2. Detailed plan map of the Mayflower pond,illustrating sample locations for this study. 648 649