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• Quartz, feldspar, and clay minerals occur as primary detrital minerals in sandstones and shales. <br />Clays, shales, and organic residues commonly have higher quantities of trace metals occurring as <br />adsorbed ions than do coarser grained strata. These ions may be released into solution as a result <br />of oxidation and low pH. Other less commonly occurring minerals found in overburden strata include <br />calcite (CaCO~, limonite (Fe2O~ and possibly siderite (FeCO,). Small deposits of copiapite (FeO4) <br />and halotrichite (Fe or Mg SOi) may occur as crusts on the faces of coal seams and associated strata <br />along outcrops near the New Horizon 2 mine area, (Caruccio et al., 1977). <br />Coal Seam Analysis. Table 2.04.6-1, Coal Seam Analysis Data, summarizes the quality of the <br />upper Dakota and lower Dakota coal seams for exploration drill holes placed within the New Horizon <br />2 permit area. <br />New Horizon 2 Overburden Assessment <br />Chemical analyses of overburden samples obtained from the New Horizon 2 study area were <br />performed by Peabody Coal Company to identify any acid-forming, toxio-forming, alkalinity producing, <br />• or other inhibitory materials present within the proposed mine boundary. Physical properties of the <br />overburden were determined to define compaction, stability, permeability, erodibility, and water <br />holding characteristics. Chemical and physical analyses also reveal the most desirable overburden <br />strata to be placed at the spoil surface and in the pit base. This baseline information is required prior <br />to mining to effectively prepare a mine plan that restores landscape productivity and which also <br />minimizes environmental degradation. Cross section E-E' has been extended to include lithology in <br />the western portion of the permit revision area (see map 2.04.6-3). Anew cross section H-H' has <br />been prepared as the dip section cross section in the area added under this permit revision (see Map <br />2.04.6-6). Revised Map 2.04.6-1 shows the location of the geologic cross sections and the <br />overburden sample locations. One of the overburden sample locations, 881 E, is used in Geologic <br />Cross Section E-E'. Revised Cross Section E-E' and the new Cross Section H-H show that the <br />overburden to be mined within the new permit revision area is of the same stratigraphic units of <br />similar lithology to that sampled at 881 E. The character of the overburden in the new permit area <br />should be essentially the same as that previously sampled. <br />• Revised 9/99 2.04.6-6 <br />