Lower Gondwana rocks are exposed as narrow bands and discontinuous patches along the western edges of the Rajmahal Hills covering a large area of the Bengal Basin, North Bengal and Purnea. Two coalfields - Hura and Chuperbhita - have productive coal mines. Pillar coal samples from the working coal seams of Hum and Chuperbhita coalfields were collected and subjected to a detailed petrographic and geochemical study using refined procedures on a large number of samples. The results of the micropetrographic study reveal that the Rajmahal coals are rich in liptinite and inertinite contents. The fluorescence microscopy indicates that a major part, identified as argillaceous mineral matter under white incident light, is composed of liptinite macerals such as bituminite fluorinite and exsudatinite. The volatile matter and reflectance suggest these coals are subbituminous to high volatile bituminous B/C in rank. The quantitative relationships among maceral and microlithotype suggest that these coals were deposited in limnic to limno-telmatic conditions under very wet conditions that resulted from undisturbed peat that developed in situ along with subaquatic (limnic) sedimentation in swampy lakes. Further, the GI and TPI values indicate that the Hura coals were formed under oxic moor conditions with sudden episodes of flooding, while the Chuperbhita coals have originated in wet moors with intermittent moderate to high flooding. In addition, G.I. values suggest the formation of these coals in an upper delta/alluvial valley with braided plains.