Metminco Limited (ASX: MNC) has announced a highly encouraging update from the re-visit of the data set and interpretation of the Tesorito gold target of Quinchia gold project, Colombia.
MNC reported that Tesorito re-assessment has confirmed significant potential of the target. The company said that a field program has been designed as a pre-curser to potential follow-up drilling.
Quinchia gold project
The Quinchia gold project is located in central west Colombia, 100km south of Medellin. The Quinchia Portfolio covers 10,542Ha consisting of granted titles and applications.
The project includes deposits and targets such as Miraflores, Chuscal, Dosquebradas, and Tesorito.
Approximately 40,000m of drilling has occurred at Quinchia and includes an established 877koz Resource and 457koz Reserve at Miraflores. Metminco earns a 51% interest in the Chuscal prospect through exploration investment.
Tesorito target
Tesorito is a sub-outcropping mineralised porphyry discovery located approximately 1km to the north of Chuscal, and only several hundred metres from the proposed processing facility as per the Miraflores feasibility study.
Work to date at Tesorito included mapping, rockchip, and soil geochemistry sampling programs, aerogeophysics (magnetic, radiometric), IP surveys and drilling.
Encouraging results
Each of the seven diamond drill holes at Tesorito had intersected significant widths of gold mineralisation within a multi-phase porphyritic intrusive complex.
Significant results include 384m @ 1.01g/t Au from 16m to end-of-hole, including 32.5m @ 1.34 g/t Au from 48.8m; and 156.6m @ 1.28 g/t Au from 88.3m (from Hole TS-DH-02) ; and 64m @ 1.67g/t Au from 144m, within 253.1m @ 1.01 g/t Au from 2.9m (from Hole TS-DH-07.
Tesorito target re-assessment conform potential
The re-assessment of Tesorito had stemmed from a geological/target review commissioned by the new Board of Metminco.
The company reported that a geological review and re-interpretation of data has confirmed the significant potential of the target.
MNC said that the re-assessment was led by the Company’s Consulting Geologist Nick Winer, who played a significant role in the discovery of the Nuevo Chaquiro copper-gold porphyry deposit 50km to the north, and confirmed the appeal of Tesorito and identified a program of work to advance the target.
The previous drill programs at Tesorito assumed that mineralization was primarily controlled by a regional N-S trending bounding structure.
However, the company said that the detailed assessment of rockchip geochemistry data suggests the gold target and porphyry pulses lie in NW-trending, low pressure zones within the N-S trending zone.
The company said that litho-geochemical mapping has revealed a N-S trending, 2km long x 200m to 600m wide zone of alteration, and gold mineralisation in soils with only ~300m of that strike tested by drilling to date.
The NW trend is consistent with known regional controls on mineralization in other deposits in the region such as Nuevo Chaquiro which is a high-grade Cu-Au porphyry just 50km to the north.
Next steps
The Company reported that it has developed a pre-drill program including extending the soil geochemistry grid, re-logging drill core, and undertaking a ground magnetics survey. This is being done to further validate the model and assist in drill hole targeting.
Extending geochemistry grid: Metminco said that the soil sampling geochemistry program will close the existing grid spacing from 200m x 50m to 100m x 50m and extend the grid to better define the target zones.
Re-logging drill core: The company said that the Tesorito drill core will be re-logged with particular attention to rock composition (lithology) and texture using litho-geochemistry and rock thin sections.
The reassessment study had identified variations in geochemistry and texture markers that were not apparent in the original core logging exercise and is expected to lead to better targeting.
Ground magnetics survey: The company said that the ground magnetics survey will provide greater resolution than the previous regional programs.
MNC said that there is a subtle but significant magnetic feature associated with the Tesorito porphyry zone which probably reflects the overall potassic alteration part of the system.
The company said that the new magnetics survey is designed to enable 3D modelling which is expected to provide useful targeting.
Metminco said that the above field programs will allow it to generate a 3D geologic model which will provide valuable information to design a follow up Tesorito drill program.
Management comments
Metminco’s Managing Director Jason Stirbinskis said: “In addition to the impressive drill intercepts, the results in holes ’07 and ’02 are geologically significant and a major catalyst for the re-assessment.
Hole TS-DH-07 was the best result at Tesorito and, most interestingly, was drilled oblique to all previous holes which has prompted a re-assessment of structures influencing the distribution of mineralisation.
Hole TS-DH-02 ended in a mineralised zone that included 2.6% Cu over 0.7m at 390.8m implying there could be a Cu- rich zone at depth.
Completing the above program in the next few months will provide the opportunity to add a validation drilling program to the back end of the current Chuscal drill program.The Tesorito target has the potential to provide additional resources to a district scale mining operation.
Metminco management is of the belief that the target remains with considerable untested potential for defining continuity of higher grade zones such as that intersected in TS-DH-007 and for evaluation of the copper potential.”
