Cerro Chato Project

The Cerro Chato project is secured by four mining properties, covering a total area of 11000 ha, which are adjacent to the La Juanita project and only a few kilometers away from the Don Nicolas Au-Ag mine. The most relevant hydrothermal features in the project are two quartz veins, of considerable extension and width, named Silvia and Alejandra, as well as other minor veins in the center and east of the project.

Fomicruz has carried out lithological mapping, rock chips sampling, magnetometry, and the collection of numerous rock and float samples (intended for XRF and spectroscopy), covering almost the whole property. The company also drilled 1020 m of diamond core, in 4 boreholes.

The Silvia vein, shows a general northwest orientation and dips 65º to the southwest. This vein has a length of 1200 meters, and an average width of 1 to 2 m, with sections reaching up to 5 m. At surface this vein is hosted by jurassic ignimbrites and tuffs of the Bahía Laura group, but at depth it is partially hosted by granodiorites and sandstones of the La Leona and La Golondrina Formations. The vein shows massive quartz, and locally some banded silica and replacement textures after calcite or barite; there are also hydrothermal breccias and stockworks.

The Alejandra vein, shows a NNE orientation and has a secondary subparallel vein at 50 to 200 m to the west. The main vein has a length of 3400 m, while the secondary one extends for about 1200 m. The veins have widths of 1 to 2 m, reaching up to 20 m in some areas of breccias and stockworks. The host rocks are permic sandstones of the La Golondrina Formation, except in the extreme south where the vein is hosted by granite of the La Leona Formation. The quartz in the vein shows mainly massive texture, although it also shows relatively abundant replacement (bladed) textures.

Chemical assays of rock chips from the Silvia vein returned anomalous gold concentrations (of up to 382 ppb) and strongly anomalous Hg concentrations (up to 3000 ppb). Rock chips from the Alejandra vein also returned anomalous Au and Hg concentrations, although lower than those from the Silvia vein.

The boreholes drilled in 2008, confirmed the continuity of the veins to a vertical depth of at least 250 m, but the concentrations of gold and silver detected were low. However, the geochemistry of the boreholes remains incomplete, since much of the drill cores were not sampled at the time of drilling, even many intervals containing abundant veinlets of quartz and sulfides.

In 2019, extra field work was carried out in the project to collect surface data and try to get a better inside of the epithermal paleo-system. In that occasion, the lithology of the most relevant portion of the project was mapped with detail, showing the presence of a few veins that had been previously been unnoticed. More than 30 rock samples were collected from those veins; some of which returned anomalous concentrations of Au, As, Cu, Pb, and Zn. In addition, magnetometric data were registered along 265 linear kilometers, and more than 5000 small samples were collected for being analyzed by portable XRF and reflectance spectroscopy, tasks that still should be completed.