The effects of mining sector growth are analysed with a five-sector general equilibrium model. The effect of the mineral discoveries is to cause the agricultural sector to contract, but to cause the import-competing sector to expand by a small amount--a result which differs from Gregory's (1976) analysis. However, a mining boom caused by increases in external demand, rather than by new discoveries, leads to a different set of results. Some likely effects of the boom on the growth rates of the different sectors in the economy are reported. Finally, the effects of an export tax on minerals are considered.