Some of the mineral matter may cause corrosion or pollution particularly during combustion. Sulphur and chlorine are such elements and are objectionable to some large Industrial consumers.
Section 7 – Shales and seat earths Shales and seat earths form the refuse in coal.
SHALE, generally found in the roof of coal seams, is usually a dull (lusterless) grey in color and is heavier than pieces of coal of the same size.
SEAT EARTH is generally found in the floor of coal seams. Light in color, clay-like or sandy, it is heavier than coal of the same size.