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9 <br />While this description may explain the present structure and mineral assemblage in <br />the Cresson deposit, the acid formation and neutralization reactions proposed have <br />occurred in a depositional state which is significantly different than we can expect <br />when the disturbed materials are deposited in disposal areas. Changes in exposed <br />pyrite and jarosite surface areas, changes in exposed areas of neutralizing <br />carbonates and aluminosilicates, and different exposure to water Oow velocities, <br />cyclic wetting and drying cycles, bacterial impacts, and freeze-thaw cycles may all <br />impact the net outcome of acid generation and neutralization reactions. <br />Characteristics of Cresson Mine Rock Based on Test Data <br />A total of thirty seven (37) drill and surface samples were subjected to characterization <br />tests and results presented in the reviewed document. The samples were chosen to be <br />representative of the potential excess overburden material from the Cresson deposit. <br />Details of test procedures to determine reported characteristics were generally reported in <br />earlier documents and in the document under review here test results were reported and <br />discussed as they related to acid-base potential of the material. Where appropriate, the <br />author has referred to the earlier reports on test details to augment the information in the <br />report under review here. <br />Test data relative to acid-base potential of the materials included results from the <br />following types of tests or analyses: <br />Sulfur Species Content <br />Modified Acid/Base Accounting ("ABA") <br />Paste pH Measurement <br />Detailed Examination of Selected Samples <br />The following section of this report addresses comments to each of these characterization <br />tests separately in the order presented above. In general, these comments relate to the <br />reported test result interpretations with respect to acid-base potential issues with the <br />Cresson overburden materials and no in-depth review of test procedures is included. <br />The suite of tests reported on include what could be termed both compositional and <br />performance tests since they address both the mineral constituents present in the <br />overburden samples and the performance or behavior of these materials in tests aimed as <br />simulating environmental exposure conditions. <br />Sulfur Species Content <br />Sulfur present in the Cresson materials can be associated with a variety of minerals and in <br />a variety of chemical forms. Analyses for total sulfur as distinguished from analyses for <br />sulfide and sulfate sulfur are based upon different analytical techniques and the assignment <br />of sulfide or sulfate sulfur to specific minerals (e.g. pyrite or jarosite) is a qualitative <br />assignment. <br />OMI.R951DEH <br />