As part of a continuing program by the U.S. Geological Survey to collect and chemically analyze representative samples of U.S. coals, 61 coal and coal-associated rock samples were collected from the Rosebud and McKay beds in the Paleocene Tongue River Member of the Fort Union Formation in Rosebud County, Montana. This area is located in the Montana part of the Powder River region, specifically within the Coistrip coal deposit as defined by Matson and Blumer, 1974. Forty of the samples (36 coal and 4 coal-associated rock) are from the Rosebud bed and 21 samples (all coal) are from the McKay bed. The McKay bed is between 5.5 and 18.6 m. below the Rosebud bed. The samples were collected from the Big Sky Mine and from 13 core holes in sec. 1, 2, and 27, T. 1 N., R. 41 E.; sec. 23 and 35, T. 2 N., R. 41 E.; and in sec. 1, 3, 5, 9, 15, and 16, T. 1 N., R. 40 E. The location of the sample collection area is shown in figure 1. Brief descriptions of all 61 samples are listed in table 1 and locations of sampling sites are shown in figure 2.
Estimated strippable coal resources for the Rosebud bed in this area exceed 1,305 metric tons (1,439 million short tons) (Matson and Blumer, 1974). There are currently no estimates of coal resources for the McKay bed from this area.
Analyses of samples D172034 through D172051 have previously been published in Swanson and others (1976) and are included here in order to provide a more complete data listing. For additional information on sulfur and trace element contents in the Rosebud and McKay coal beds, see Chadwick, Woodriff and others (1975) and Chadwick, Rice and others (1975).
