Aguia Resources has reinterpreted its high-grade, polymetallic gold-copper-silver-zinc El Dovio play in Colombia as an orogenic lode gold-silver style of mineralisation that was later followed by copper and zinc.
The company’s new designation contrasts sharply with its previous casting as a volcanogenic-hosted massive sulphide (VMS/VHMS) deposit and indicates that the base metal component results from emplacement during later tectonic processes. The El Dovio property hosts high-grade polymetallic gold-copper-silver-zinc mineralisation of up to 16m going 11.7 grams per tonne gold including 1m at 104g/t in a trench cut within an extensive belt of metamorphosed Cretaceous-age volcanic rocks.
And the company plans to back up its new theory with a targeted drilling campaign likely to be rolled out next year.
As a result of its review, Aguia says El Dovio does not meet the common characteristics of VMS and VHMS deposits and is more accurately portrayed as a different deposit type. It says it could even be a combination of deposit types fitting an early orogenic lode-gold style of mineralisation for a gold and silver mineralising event, followed by the later emplacement of zinc and copper as part of an evolving tectonic environment.
While no resource has been estimated, drilling results to date suggest the potential for a high-grade underground resource that bears similarities to Sandfire Resources’ renowned Degrussa copper orebody.
Previous Canadian explorer Newrange Gold Corp, through its subsidiary Colombian Gold Mines, drilled 34 diamond holes between 2012 and 2014 and returned a host of handsome intercepts including 2.1m at 15.6g/t gold, 20.31g/t silver, 2.24 per cent copper and 2.09 per cent zinc in one hole. Another hole gave up 6.85m at 5.86g/t gold, 5.89 per cent copper, 34.29g/t silver and 1.29 per cent zinc, while other holes also featured tantalising grades.
The 34 holes have provided Aguia with valuable information to support its re-designation and an exploration adit has already been constructed. Based on the new model – and incorporating regional structural trends that coincide with the known mineralised trend in the deposit – management believes there is a strong likelihood that the copper-zinc replacement zones will be repeated, opening up the possibility for repeated targets along strike.
The revised geological model opens the pathway for a different approach to exploration within relevant parts of Colombia’s Western Cordillera and the possibility of multiple parallel shear zones hosting gold mineralisation.
Aguia’s new interpretation addresses some key concerns regarding the model erected by Colombian Gold Mines, which significantly extended the strike of the polymetallic mineralisation at the deposit. That company’s earlier work, including diamond drilling, showed that gold-copper-silver-zinc mineralisation occurred between 10m and 68m width in outcrop along about 1km of strike and extended to more than 200m depth.
It is interesting to note that metallurgical testwork previously conducted on a 53 kg bulk sample by Nevada-based McClelland Laboratories on behalf of Colombian Gold Mines, showed recoveries of 96.4 per cent for the gold, 97.8 per cent for copper, 91.1 per cent for silver and 96.8 for the zinc. Aguia believes the high standards would report to a concentrate.
Now, with past work at El Dovio providing a strong platform, the company believes it has the right base from which to launch into proving it has an advanced exploration project that is flying under the radar firmly within its grasp.
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By Doug Bright
