A preliminary report on a zone containing thick lignite beds, Denver Basin, Colorado

Abstract

A zone of lignite beds of Paleocene age in the Denver Formation (Upper Cretaceous and Paleocene) lies about 800-1,500 feet above the well-known and extensively mined coal beds of the Laramie Formation (Upper Cretaceous). The zone is a few hundred to as much as 500 feet thick. Where lignite beds lie within 1,000 feet of the surface, this zone underlies an area about 30 miles wide by about 75 miles long, stretching from just northeast of Denver to several miles south of Calhan. Fifteen mines were operated at various periods between 1874 and 1940 and probably produced a total of less than 100,000 tons of lignite, mostly for local use. the base. Available analyses indicate that the following general figures, on an as-received basis, may be applied to relatively clean lignite from this zone: 6,000-7,000 Btu, 20-35 percent moisture, 8-18 percent ash, and 0.3-0.5 percent sulfur. Rank of the lignite is lignite A as calculated by the formulas of the American Society for Testing and Materials (ASTM), although some parts, especially of deeper beds, may be as high as subbituminous £ coal in rank.Best utilization of the lignite probably would be by gasification, liquefaction, or similar methods, because of the numerous non-coal partings and low quality.The thickest known lignite bed is estimated to contain at least 1.25 billion short tons of lignite. Two methods of roughly estimating the order of magnitude of lignite resources, in beds at least 4 feet thick and within 1,000 feet of the surface in this zone, indicate resources are on the order of 20 billion tons.

Water quality at a biosolids-application area near Deer Trail, Colorado, 1993-1999

“…Lignite, a type of coal, was mined from the Laramie Formation (Soister, 1974) and was known to be present in the vicinity of the study area as thin, discontinuous layers in the bedrock or as weathered alluvial material that may or may not be present at any specific well. Alluvium in the study area consisted of glacial loess and outwash (minerals likely included montmorillonite, quartz, feldspar, biotite, pyroxene) and weathered conglomerates, sandstones, siltstones, and shale (minerals likely included montmorillonite, quartz, feldspar, gypsum, and calcite) (B.F. Jones, U.S. Geological Survey, oral commun., March 22, 2000).…”