Knobloch clinker, Southern Montana, 1999 National Coal Resource Assessment (knclkg.shp)
The clinker theme represents a digital polygon coverage
showing areas where clinker is present.  Clinker forms from
the natural burning of coal beds in outcrop, and consists of
baked (melted) and fused rocks that are commonly red or
red-brown in color.  In this coverage, only clinker formed by
the burning of the …