In India coal occurs in rock series of two main geological ages, namely Gondwana, a little over 200 million years in age and in tertiary deposits which are only about 55 million years old. The major resources of Gondwana coal, which are metallurgical coal, are located in Damodar valley (West Bengal-Jharkhand). Jharia, Raniganj, Bokaro are important coalfields. The Godavari, Mahanadi, Son and Wardha valleys also contain coal deposits. Tertiary coals occur in the north eastern states of Meghalaya, Assam, Arunachal Pradesh and Nagaland. Jharkhand is the largest producer where Jharia, Bokaro, karampur, Palamu are the major coal fields. In West Bengal, Raniganj, Jalpaiguri and Darjeeling are the coal fields. Sarguja, Bilaspur, Raigarh and Bastar districts are coal fields found in Chhatisgarh. M.P. has coal fields in Chinaware district and in Maharashtra, Chanda is the main field.