A zinc silicate ore was treated with sulfuric acid in a water-starved system in the presence of microwave irradiation. Phase changes occurring during the reaction process were examined by X-ray powder diffraction analysis and the effect of microwave irradiation time and water amount used on the extraction of zinc, silica and iron was investigated. It is demonstrated that the hemimorphite present in the ore is predominantly changed to ZnSO4.6H(2)O for samples without microwave irradiation and ZnSO4.H2O for those with microwave irradiation, respectively. Silica and iron are changed to quartz and Fe(OH)(3). An increase in microwave irradiation time can slightly increase the extraction of zinc and decrease the dissolution of iron. The increase of water amount used can increase the extraction of zinc and considerably decrease the dissolution of silica. Under optimum conditions, the extraction percentage of zinc is 99.08% and the dissolution of silica and iron is as low as 0.30% and 0.10%. (C) 2002 Elsevier Science Ltd. All rights reserved.