The Indian Coal deposits mainly occur in two stratigraphic horizons: Permian Gondowana and the Tertiary. The Gondowana coal contributes about 99.5% of total coal deposit in India and the Gondowana coal formation is mainly confined within the Peninsular India.The Gondowana Coalfield covers nearly 2% of the total area of India. The prominent coal seams in the Gondowana belongs to the Kaharbari (Basal Coal Measures) and Barakar (Lower Coal Measures). The Raniganj Formation (Upper Coal Measures) contains the bulk of the superior grade non-coking coals in India. Most of the Gondowana coal formations are found along with distinct river valleys such as Damodor-Koel, Son-Mahanadi, Pranhita-Godavari and Satpura area. The Rajmahal coalfields are located north-east of Damodar Valley. Most of the Gondowana Coalfields except the Godavari Valley are operated by the Coal India Limited.
General Gondowana Coal Quality:
- Mainly sub-bituminous to bituminous in rank.
- Usually high ash content (generally 15% or higher)
- Average heat value: 5000Kcal/Kg
- Moisture content is variable between 6-10% (Only exception is Barakar Coal with low moisture content).
- Volatile Matter – low to medium in most coals.
- Sulfur content is typically low and rarely exceeds 0.6%.
- Average reflectance between 0.5 to 1.
Thickness of Gondowana Coal seams:
- Generally think to very thick.
- Lower Barakar formation has 65 feet – 130 feet thick coal
- Damodar Valley coalfields: 40 feet – 50 feet thick coal
|Lower Cretaceous||Umia and Jabalpur Formation||Thin coal seams, mainly in Gujrat|
|Lower Jurrassic||Kota and Chikiala Formations||Thin coal seams, mainly in Satpura and Godavari|
|Upper Permian||Ranijanj Formation||Peninsular India and Himalayan foothills|
|Middle Permian||Barren Measures|
|Lower Permian||Barakar and Kaharbari Formations|
Major Coalfields in Gondowana with active mines:
- Eastern Coalfield Ltd: Raniganj, Rajmahal and Saharjuri Coalfields
- Bharat Coking Coal Ltd: Jharia and Raniganj Coalfields
- Central Coalfields Ltd: East and West Bokaro, Ramgarh, Karanpura, South Karanpura, Daltonganj, Hutur, Giridh, Jainti coalfields
- Western Coalfields Ltd: Umrer, Kamptee, Chanda-Warda, Pench-Kanhan, Pathakhere coalfields.
- Southeastern Coalfields Ltd: Umaria, Johilla, Sohagpur, Jharkhand, Sonhat, Jhilmili, Chirimiri, Bishrampur, Korba, Mand-Raigarh, Ib-Valley and Talcher coalfields
- Northern Coalfields Ltd: Singrauli coalfields.
Reference: R.V. Savanur and A.K Roy in 1988: Paleobotanist v 36, pp 369-377. (Check the paper for detailed Gondowana Coal Quality analysis)