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rock with the unweathered rock which provides benefit in reclamation as the leached and <br />oxidized weathered rock is more suitable for reclamation than is the unweathered rock. <br />Mineralogy. Iron disulfides (pyrite [FeS2] and marcasite [FeS2]) are present in the unweathered <br />bedrock strata. These minerals are associated with carbonaceous and coal - bearing rocks in <br />which reducing conditions are prevalent at the time of deposition. When exposed to an oxidizing <br />environment in the presence of percolating water, iron disulfides often react to form hydrous iron <br />sulfates. These compounds commonly appear as white and yellow salt crusts on weathered rock <br />surfaces. According to Caruccio et al. (1977), the rate at which these acid leachates are <br />produced is dependent on the quantity and grain -size distribution of pyritic material, availability <br />of oxygen, presence of iron bacteria, amount of calcareous material, and relationship to the <br />ground water aquifer. According to Nordstrom (1982), framboidal pyrites are the most reactive <br />form of pyrites, while massive pyrite or nodules react very slowly. Pyrite nodules are common <br />in unweathered bedrock and coal in the NHN permit area. <br />The mineral gypsum (CaSO4 -2H20) is found in unweathered rock as a primary mineral and in <br />weathered rock as a secondary diagenic mineral. Gypsum is soluble in water and, according to <br />Hounslow et al. (1978), "precipitates readily from solutions produced by the oxidation of pyrite <br />coupled with the dissolution of limestone" or a calcareous sandstone or siltstone. As gypsum <br />occurs both as primary and secondary minerals in the NHN area strata, a similar cycle of solution <br />and precipitation can be expected in spoil materials. <br />Quartz, feldspar, and clay minerals occur as primary detrital minerals in sandstones and shales. <br />Where as calcite (CaCO3) is found as both a primary and secondary mineral. Clays, shales, and <br />organic residues commonly have higher quantities of trace theta's occurring as adsorbed ions <br />than do coarser grained strata. These ions may be released into solution as a result of oxidation <br />and low pH. Other less commonly occurring minerals found in overburden strata include <br />limonite and hematite (Fe2O3) and possibly siderite (FeCO Hematite and limonite are the <br />oxidation products of the iron sulfides (yellow to rusty red) and siderite and are obvious in the <br />weathered rock. Small deposits of copiapite (FeO4) and halotrichite (Fe or Mg SO4) may occur <br />as crusts on the faces of coal seams and associated strata along outcrops near the NHN permit <br />area, (Caruccio et al., 1977). <br />Coal Seam Analyses. Table 2.04.6 -1, Coal Analyses, summarizes the coal quality of the UD1 <br />Seam and LDx Seam for exploration core holes that were drilled within the proposed NHN <br />permit area. Core holes that were drilled in the area of the old Peabody Nucla Mine were, <br />however, removed from the sample list because that coal has been removed. The analyses reflect <br />the expected quality with dilution from roof and floor added. The average values are simple <br />arithmetic averages and are not weighted by thickness or tonnage. Table 2.04.6 -1 illustrates <br />that: the coal in the LDx Seam is significantly better than that of the UD1 Seam; coal quality <br />from holes located with shallow overburden ( less than 25 ft. or so) are significantly lower in <br />quality than holes with deeper overburden; and the core holes located in shallow overburden are <br />higher in moisture and lower in sulfur content. The difference in quality relative to depth is the <br />Section 2.04.6 Page 6 April 2011 <br />