Effect of igneous intrusive on coal microconstituents: Study from an Indian Gondwana coalfield

►Coals intruded by a dolerite dyke show changes in the microconstituents. ►Affected coals show devolatisation vacuoles, high reflectance and low fluorescence. ►Injected mineral matter indicates the impact of thermal metamorphism. ►Close to the intrusive, pollen/spores were charred beyond recognition. ►Presence of unaltered pyrite indicates temperature did not rise more than 500 °C.