Summary:
All data is sourced from the EIS Report 2012 and has been translated from Spanish with the assistance of AI.
The deposits in the region where the project is located are located on the shores of a Cretaceous platform made up of calcareous rocks mixed with volcanogenic sulfide deposits. The surface geology is constituted by the presence of metavolcanic materials, shales-sandstones, shales-phyllites, tuffs, deformed breccias, agglomerated tuffs, breccias and lavas.
The mineralized deposits of the region are volcanogenic deposits of massive zinc-lead-copper-silver-gold sulfides, located approximately 150 kilometers southwest of Mexico City. The presence of oxides and sulfides of zinc, lead and copper, with values of gold and silver in the mantle area, known specifically as Rey de Plata (since the early 1900's). In fact, there are vestiges of what was once an oxide foundry in this area; However, it was not until the end of the seventies, when mineral bodies began to be found, in the form of lentiform sulphides, projecting towards the southwest, the dip of the Rey de Plata outcrops. At that time, around two million tons of ore were estimated based on 52 diamond drill holes.
In the area that houses the project's deposits, four main lithological units are located. The oldest one is composed of intensely chloritized andesitic volcanic and volcanoclastic rocks. Overlying the andesitic units in a concordant manner are felsic pyroclastic rocks, interbedded with black shales. Andesitic volcanic rocks are also present as interbedded layers at the top of the felsic unit. Pressing against the andesitic and felsic units are calcareous carboniferous limestones, interbedded with clays and siltstones.
The mineralization at the bottom of the Tehuixtla body consists mainly of pyrite and chalcopyrite. At the top there are sphalerite, sulfosalts and galena. Gold is located mainly in the lower silicified zone. In this body, three mineralized zones called “yellow ore” (massive sulfides) and “mixed ore” (disseminated sulfides with a higher silver grade) have been determined.
The lower andesitic unit is likely several miles thick and comprises the main part of the volcanic package where the mineral deposits are located. The upper part of the andesitic unit consists of several pyroclastic, epiclastic, and lava bodies tens of meters thick. The lower andesitic units, as well as the higher ones, are heavily chloritized. The andesite is cut by abundant veins of calcite and ankerite. The mineralization beneath the Tehuixtla body consists mainly of pyrite and chalcopyrite. Above, there are sphalerite, sulfosalts, and galena. Gold is mainly located in the silicified zone at the bottom. In this body, three mineralized zones have been determined, named "yellow ore" (massive sulfides) and "mixed ore" (disseminated sulfides with a higher silver grade).