The Fenix Gold Project is 100% owned by Fenix Gold Limitada, a subsidiary of Rio2 Limited, and is subject to a streaming agreement with Wheaton Precious Metals.
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Summary:
The Fenix Gold Project is located near the summit of the Cerro Maricunga Volcanic Complex, where it hosts a NW-SE-trending oxidized gold system approximately 2.5 km long, 0.75 km wide and 600m deep.
The stratigraphy of the Project is characterized by the following geologic units: 1) a pre-mineral unit (Early Phreatomagmatism Unit) formed by a set of domes and lava-domes which are rhyodacitic to andesitic and which intrude a sequence of block and ash pyroclastic breccias; 2) a syn-mineral series (Phreatomagmatic Unit) of massive-to-stratified ash tuffs, fine-to-medium lapilli tuffs, breccia tuffs and pyroclastic breccias of phreatomagmatic origin and with subvolcanic intrusions which are genetically related; and 3) a post-mineral group of small-volume dacitic domes that crosscut all previous units (Late Phreatomagmatism Unit).
The Phreatomagmatic Unit is associated with at least 10 maar-diatreme-type volcanic structures (maar-diatreme field) of different preservation degrees, which have been crosscut by NW-SE and late NE-SW faults and fractures.
The gold mineralization is hosted mainly by tuffs, breccias, and dacitic subvolcanic intrusions from the Phreatomagmatic Unit and, to a lessor extent, by andesites and dacitic domes of the same unit. The high-grade gold is commonly associated with low-temperature black banded quartz veins (BBV), which occur in sheeted veins, stockworks, subangular fragments in phreatomagmatic breccias and in hydrothermal injections of silica-magnetite. Low-grade gold is also present in veinless rocks as microscopic auriferous magnetite/ilmenite disseminated in a breccia matrix. Copper sulfides such as chalcocite-digenite, chalcopyrite and bornite have also been detected as small inclusions in quartz.
The deposit is interpreted as an intrusion-related, low-sulfidation, quartz-sulphide, Au±Cu deep epithermal mineralization, which has been lately remobilized by supergene processes facilitated by the permeable fine-grained matrix of the phreatomagmatic breccias.
The alteration associated with the mineralization is a weak homogeneous argillization represented by nontronite, silica, magnetite (chlorite), and, to a lesser extent, restricted silicification. Removed from this alteration, a ring-shaped kaolinite-hematite halo affects the country rocks, likely due to supergene alteration derived from disseminated pyrite.
The Project is located in the central summit of the CMVC, where it hosts a NW-SE trending oxidized gold system of 2.5 km long by 0.75 km width average. Mineralized zones named Fenix North, Fenix Central and Fenix South have been defined based on gold distribution, trenches, outcrops, and drill holes.
The Project hosts an oxidized gold system of 2.5 Km long by 0.75 Km average width that trends NWSE. Drilling has confirmed gold mineralization’s existence at depths of at least 600 m. The economic mineralization from the surface presents continuous values greater than 0.5 g/t Au for more than 100 m, as it has been recognized through trenches.
The Phreatomagmatic Breccias and dacites from the Subvolcanic Intrusion unit mainly host gold mineralization. It is also found, in less extents, in andesites and dacitic domes from the Subvolcanic Intrusions unit close to the contact with the Phreatomagmatic Breccias. No mineralization is identified in the Late Domes and Blocks and Ash Pyroclastic Rocks units.
The first-order geometry of the mineralized bodies is defined by the cone morphology of the maardiatreme structures. Second-order geometries are determined by enrichment associated with faults within the maar-diatreme system and at least two subsequent episodes of veins, linked to the emplacement of subvolcanic intrusions.
The occurrence of high-grade gold is commonly associated with low-temperature dark bands bearing quartz veins known as Black Banded Veins (BBV). These structures occur as sheeted veins and stockwork in breccias, subvolcanic intrusions and domes, and are contained in subangular fragments in phreatomagmatic breccias. High-grade mineralization is also recognized in hydrothermal injections of silica-magnetite. Low grade gold or anomalous values are also present in rocks without veins. This may be explained by the microscopic presence of auriferous magnetite/ilmenite disseminated in the breccia matrix.
Mineral and mineral release studies on blasting material by Quantitative Evaluation of Minerals by Scanning Electron Microscopy (QEMSCAN) and Trace Mineral Search TMS) in ALS Vancouver (Canada) indicate Au occurs in an average size of 3 µm mainly free (48% to 77%) and adhered to/included in gangue minerals (quartz>pyrite). Chalcopyrite, pyrite, and sphalerite are less than 0.1%, and ultratraces of galena, pyrrhotite and bornite are also identified (ALS, 2021).
Occurrence and paragenesis studies on high grade (>1.50 g/t Au) diamond core samples by TESCAN microscope in Cem Geoatacama, Coquimbo (Chile) indicate gold is not only associated with quartz but also with Fe oxides such as hematite-magnetite and copper oxides. Copper sulfides like chalcocite-digenite, chalcopyrite and bornite as small inclusions (5 µm to 25 µm) in quartz are also detected.
These findings are consistent with the interpretation by Corbett (2019) that the mineralization in the Project is an intrusion related, low sulfidation, quartz-sulphide Au±Cu deposit of deep epithermal type. This same author considers the deposit was lately remobilized by supergene processes facilitated by the permeable fine-grained matrix of the phreatomagmatic breccias.