Gold mineralisations in the SW Iberian Pyrite Belt

The occurrence and distribution of gold in the massive sulfide orebodies of the upper Palaeozoic volcano-sedimentary environment of the SW Iberian Pyrite Belt have long been assumed to be quite uniform. Recent investigations in several working mines indicate that the gold content of the ores varies between ore types, and is controlled by physico-chemical and time factors during deposition. Above-average gold grades occur in the following ore types: lead-zinc-rich ores, situated laterally and on top of the massive sulfide lenses; copper-rich siliceous basal ore facies; footwall stringer sulfides; and gangue-rich massive sulfides (siliceous, carbonate-rich, baryte bearing, or carbonaceous matrix). Exploration possibilities therefore are promising in foot- and hanging-wall environments within an orebody, as well as in disseminated and stringer ores in its footwall.