Alteración supergénica de sulfuros en algunos yacimientos del SE de Espana. Nota preliminar

Abstract

The two areas selected in this paper correspond to S. Almagrera (Almeria) and “Cabezo S. Cristobal” (Mazarron, Murcia). Both went exploited to obtain Pb, Zn, Fe and Ag and subsecuently baryte (S. Almagrera), being at the present time all the mining works abandoned. Both areas present a similar mineralization, standing out for its economic interest the bearing Ag galena, sphalerite and pyrite assemblage, with other sulphides and sulphosalts as minor phases. However, the geological setting in which mineralizations occur is very different. So, in S. Almagrera de wall-rocks of the veins are schists and micaschists of "Alpujarride complex", while in the Mazarron area the orebodys occur within the calcalkaline volcanic materials, developed during Tertiary in the SE of Spain. The weathering processes of these two areas have not sufficiently known, from a mineralogial and geochemical point of view. In this paper, a preliminary note over these processes is pointed out. Such weathering processes can be studied in two different groups. The first one, developed over the veins and wall-rocks and the second one, related to the dumps. The second group corresponds to the most developed weathering processes, which are convergent on both two areas. The mineralogical association is similar and the main phases are: jarosite, alunogen, halotrichite, melanterite, coquimbite and other soluble sulphates. An advance of the chemical composition of the weathering products points out the systematic presence of a large number of chemical elements as Pb, Zn, Fe, Mn, Al, Mg, Ag, Cu, Cd, As, Ge, Sb, and Bi among others.