Section 27(1)(d) in The Mineral Conservation And Development Rules, 1988
(d)unless otherwise provided, be on a scale having a representative factor of-(i)200:1 in case of mica mines and other mines having small-scale workings below ground;(ii)2000:1 in case of mines having large open cast working and also in case of surface plans of large leasehold areas; and(iii)1000:1 in other cases: