In turn, as surplus-value passes through the circuits of industrial, money and commodity capital, it takes the form of profit of enterprise, of interest, and, in the case of land-based production, of ground-rent, whereby a quite stable absolute ground-rent is secured by holders of title to land and a differential ground-rent arises from variations in the productivity and profitability of mineral deposits once constant capital and variable capital are applied to them.
As the ratio between constant capital and variable capital shifted in favour of constant capital, this led to the associated tendency for the rate of profit to fall, as evidenced in lower extraction of gold per unit of labour-power from mechanised mining than from surface mining.
Although Australia's mining booms differed in their historical origins, in their main commodities, in their particular durations and in their specific impacts, the conceptual framework applied to each of the booms in this review has established the explanatory potential of the interrelations between the organic composition of capital and the rate of profit; the accumulation of constant capital and variable capital; the combination of absolute surplus-value with relative surplus-value; and the appropriation of absolute ground-rent and differential ground- rent.