TYPES OF RESERVES

* Proved Reserves: In this case, the reserves are estimated from dimensions revealed in outcrops, trenches, mine workings and boreholes and the extension of the same for reasonable distance not exceeding 200m on geological evidence. Where little or no exploratory work has been done, and where the outcrop exceeds one km in length, another line drawn roughly 200m in from outcrop will define a block of coal that may be regarded as proved on the basis of geological evidence. (Boreholes at 400 m and borehole density of 8-9 per Sq.Km.)

* Indicated Reserves: In the case of indicated reserves, the points of observation are 1,000 m apart, but may be 2,000 m for beds of known geological continuity . Thus a line drawn 1,000 to 2,000 m from an outcrop will demarcate the block of coal to be regarded as indicated (Boreholes at 1 to 2 km and borehole density of 1-2 per Sq.Km.)

* Inferred reserves : This refers to coal for which quantitative estimates are based largely on broad knowledge of the geological character of the bed, but for which there are no measurements. The estimates are based on an assumed continuity for which there is geological evidence, and more than 1,000 to 2,000 m from the outcrop. (Boreholes at > 1 Km)