Methods for inhibiting depletion of mineral values from pregnant lixiviant solutions comprise contacting the requisite metal ore with a preg-robbing inhibition agent (PRIA) comprising (I) alkyl polyglucoside surfactants; (II) imidazoline based amphoteric surfactants; (III) hydroformylation products of lower (C.sub.2 C.sub.8) alkanes in an organic solvent medium, and (IV) esters and aldehydes.