Abstract: A method of activating a mineral species wherein the mineral species is activated by fine or ultra fine milling prior to processing by methods of oxidative hydrometallurgy. The milled mineral species may be subjected to oxidative leaching under relatively mild conditions of pressure and temperature due to the milling producing minerals which are activated, and which thus react far more readily with oxidants such as oxygen. Furthermore, the oxidative leaching is able to be conducted under conditions requiring less than stoichiometric levels of oxidant, again due to the activated nature of the minerals.