Settled Land Act 1958

In a mining lease—

the rent may be made to be ascertainable by or to vary according to the acreage worked, or by or according to the quantities of any mineral or substance gotten, made merchantable, converted, carried away or disposed of, in or from the settled land, or any other land, or by or according to any facilities given in that behalf; and

the rent may also be made to vary according to the price of the minerals or substances gotten, or any of them, and such price may be the saleable value, or the price or value appearing in any trade or market or other price list or return from time to time, or may be the marketable value as ascertained in any manner prescribed by the lease (including a reference to arbitration), or may be an average of any such prices or values taken during a specified period; and

a fixed or minimum rent may be payable, with or without power of the lessee, in case the rent, according to acreage or quantity or otherwise, in any specified period does not produce an amount equal to the fixed or minimum rent, to make up the deficiency in any subsequent specified period, free of rent other than the fixed or minimum rent.

A lease may be made partly in consideration of the lessee having executed, or agreeing to execute, on the land leased an improvement authorized by this Act, for or in connexion with mining purposes.