Section 70(3)(a) in The Ajmer Abolition of Intermediaries and Land Reforms Rules, 1955
(a)Where royalties are payable on account of mines and minerals the average income on account of the royalties calculated on the basis of the Annual Return filed by the Intermediary for the Assessment of cess or income-tax during the period of 12 years immediately preceding the date of vesting or for any short period for which such Returns have been filed.