The Oil Drum

Part of the problem with coal is that, when it was first grown (as in the peat bogs back when) the region was occasionally inundated with floods, and, as the Hurricanes showed last year, this carried mud and sand into the bog. Over the passage of time, as the bog turned from peat to brown coal, and then into coal itself, these dirt bands turned into sandstone, mudstones and other rocks. The layers are often found inter-layered within a coal seam, either as very thin stringers, or as partings that can separate a single seam into layers that end up several feet apart. The bedding planes and vertical joints (referred to as cleat) provide the permeable paths through the coal, and are often partially filled with additional minerals that deposit out of the water that percolated through the coal at one time. This can also introduce lenses of pyrite and calcite, so that coal is not the simple carbon lump that people often anticipate.

This is another in the short technical posts that show up at weekends, dealing with one aspect or another of fossil fuel production. Given that, as Super G noted the Governor of Montana was on 60 minutes tonight, it seemed like a good time to return to a coal-related theme. A list of related posts will be appended at the end of this one, and relate to the mining of coal, either on the surface or from underground, though it is the surface mining of coal, that currently entices the Montana Governor. It should be noted that the adjacent state of Wyoming produces around 400 million short tons a year of coal, about ten times the current production from Montana.