San José is a metasomatic deposit, produced by hydrothermal replacement, with epidote-garnet skarns located in the contact zone between a Cretaceous limestone unit and a granodioritic intrusive. The mineralization is primarily composed of magnetite, with minor hematite. Accessory sulfide minerals including pyrite and chalcopyrite are also present.

The San José Mine is a production stage iron ore mine. Ore is mined from the open pit using conventional mining methods.

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Ore is mined from the open pit using conventional mining methods and processed into a pre-concentrate by a crushing and screening circuit with dry magnetic separation. The preconcentration facilities at the mine include one primary crusher, one secondary crusher, a dry cobbling high-intensity magnetic pulley and one tertiary crusher. The pre-concentrate is then shipped 30 kilometers by road to a rail head located in Quila, where it is railed 450 kilometers to the El Volcan concentrator. The concentration plant at El Volcan includes two ball mills, a magnetic separation circuit, flotation systems, a belt conveyor filter and a disposal area for tails. The major port installations include a tippler for railroad cars, a conveyor, transfer towers and two ship loading systems. At El Volcan the pre-concentrate is milled and concentrated via wet magnetic separation to produce the final concentrate. The final concentrate is transported 150 kilometers by rail to the Port of Guyamas where it is l ........