Explanation:

Coal is one of the most widely exploited fossil fuels in world. Coal is one of the key natural resources of Assam. It is estimated that Assam has about 371 million tonnes of coal reserves. Assam coal have high calorific value, low ash content high percentage of sulphur and low oxygen content. On the basis of chemical composition and physical characteristics, Assam coals are classified as the sub-bituminous type.Coal in Assam was first recorded by British Surveyor Lieutenant Wilcox in year 1825. First coal mining was done by C. A. Bruce in 1828. Initially British authorities were less curious about Assam coal. Popularity of tea cultivation, extension of railway lines and increasing navigation through steamships, increased the demand of coal.