Washability testing data were obtained for samples of Upper Freeport coal-bed facies (mappable subunits). The facies, which were identified and correlated using core and mine-face descriptions, are relatively uniform in thickness as units and vary less in quality than the entire bed because the number of facies are not the same throughout the deposit. Washability characteristics of a coal bed were inferred from collective megascopic descriptions, x-ray radiographic analyses, and coal-quality characteristics of the facies. In addition, certain petrographic, physical, and chemical data such as inertodetrinite content, pyrite forms, density, and contents of Zr and La of coal-bed facies samples were related to washability characteristics such as weight percent of recovery and pounds of sulfur/million Btu of recovery for a particular specific gravity of separation.

Petrographic characterization of pyrite forms and associations, weight percent of pyritic sulfur, and density were used to estimate sulfur cleanability in the samples. Good estimates of product recoverability at specific gravity float levels were made from the density of the unprocessed samples. Sulfur variability (1) is commonly greatest in the uppermost facies of the Upper Freeport coal bed, (2) results from variability in the amount of different pyrite forms (irregular pyrite that replaced organic matter), and (3) has a positive correlation with the lithology of the overlying rock. Specifically, sulfur is commonly highest in those facies overlain by sandstone.

Facies analysis of a coal bed provides data that are more reliable for the assessment of coal-bed quality than are data from whole-bed analyses. In addition, stratigraphic data, such as the quality and extent of coal-bed facies, can aid in evaluating coal beds for mining and preparation as well as in interpreting the conditions of paleopeat formation.

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