The present paper entails the role of different pyrite forms during desulfurization of Nagaland coals of north-east India. This coal contains a considerable quantity of pyrite which occurs in various forms like framboidal, disseminated, cavity and fissure fillings, massive replacement and discrete grains. The discrete pyrite grains show strong affinity with liptinite and inertinite macerals while rest of the forms show low to moderate correlation with different macerals. The correlation between different pyrite forms and desulfurization reveals that the coal samples rich in disseminated pyrite have undergone minimum desulfurization followed by framboidal pyrite rich coal samples. These pyrite forms probably caused difficulty in desulfurization due to their small size, complicated structure and their highly scattered occurrences. The maximum removal was observed in samples rich in cavity and fissure filling pyrite. (c) 2012 Elsevier Ltd. All rights reserved.