Coal deposits in the Satui area of South Kalimantan were formed in Tertiary sequences in paralic to neritic environments. The coals are mainly bright-banded and banded, with vitrinite and liptinite as dominant macerals. Mineral content is high in most coals, with a correlation between lithotype and petrographic composition. Brighter coals are associated with vitrinite-rich coal due to geologic factors. The Eocene coals range from brown coal to high volatile bituminous, indicating normal regional coalification.