An Example of the Origin of CoalBalls ScienceDirect
The coalball discovery helps fill a stratigraphic gap in coalball occurrences in the upper Carboniferous (Bolsovian) of Euramerica. The autochthonous and hypautochthonous coalballs have a similar mineralogical composition and are composed of siderite (81), dolomiteankerite (019%), minor quartz and illite, and trace amounts of ...