This project investigated alternative lixiviants for leaching copper from chalcopyrite and conichalcite, two highly refractory Cu ore minerals. Chalcopyrite (CuFeS2) is the most abundant of the copper sulfide minerals; conichalcite (CaCuAsO4OH) is less well known but contributes to supergene Cu inventory in high-As deposits. Neither leaches well in sulfuric acid. Sulfurous acid, glycine, methanesulfonic acid (MSA), and thiourea (for conichalcite leaching test) were tested as lixiviants for chalcopyrite- and conichalcite-bearing ores with ferric sulfate or hydrogen peroxide as oxidant. The highest Cu extraction from chalcopyrite was obtained by MSA (47% Cu recovery in 30 g/L of MSA with 5 g/L Fe3+ at 75 °C within 96 h; nearly 100% Cu extraction in 30 g/L MSA with 3% hydrogen peroxide at 75 °C within 72 h). Glycine recovered 20.7% of copper from chalcopyrite at room temperature within 96 h. All these compare favorably to the results of sulfuric acid leaching of chalcopyrite (1.5% recovery at 96 h). Conichalcite proved less refractory to sulfuric acid (46–71% extraction in 10 g/L H2SO4 with 3 g/L Fe3+ in 24 h) and leached almost as well in MSA (45–67% extraction in 20 g/L MSA with 3 g/L Fe3+ in 24 h), but glycine, thiourea, and sulfurous acid did not effectively leach conichalcite.