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Orosur Mining Inc. provides Colombia update

Published by
Global Mining Review,

Orosur Mining Inc. has announced an update on the progress of exploration activities at the company’s flagship Anzá project in Colombia.

Exploration work at Anzá is under the operational control of the company’s joint venture (JV) partner, Minera Monte Águila SAS. Monte Águila is a 50/50 JV between Newmont Corp. and Agnico Eagle Mines Ltd and is the vehicle by which these two companies jointly exercise their rights and obligations with respect to the exploration agreement with venture option over the Anzá Project.

Assay results from the final five holes drilled at the APTA prospect have been received. In general, the results reflect lower levels of gold anomalism compared to previously drilled holes, but show some high-grade base metal results, similar to intersections from previous drilling, adding support to the theory of hybrid volcanogenic massive sulfide (VMS)/intermediate-sulfidation epithermal system.

While few significant gold intercepts were recorded, this was not wholly unexpected as these holes were drilled to better define the geological and structural context of the APTA environment whilst the company awaited mapping, sampling, geophysics and land access to be finalised on the northern prospects.

These results would suggest that while APTA remains a highly prospective target, with multiple thick and high-grade intersections having been previously recorded, it is also complex and has substantial depth extent that is beyond the capacity of the current drill rig fleet to test.

As previously announced on 25 April 2022, drilling ceased at APTA in late March, with the remaining Colombian rig being mobilised to the Pepas prospect at the far northern extent of the project area. The focus of the scout drilling programme in the NE of the project area is to test several anomalous targets identified through surface mapping and sampling, geophysics, and geochemistry – it is planned to have four rigs operating in this area, with two each at Pepas and Pupino.

Assay results

Assay results from the final five holes drilled at APTA have been received from the ALS laboratory in Lima, Peru (MAP-101 to 105). Key intersections from these holes are noted below:

  • MAP-102: 4.85 m at 0.51g/t gold (Au), 1.24 g/t 0.16% zinc (Zn).
  • MAP-103:
    • 0.75 m at 3.3 g/t Au, 0.86 g/t silver (Ag), 0.14% Zn.
    • 0.95 m at 4.9 g/t Au, 3.49 g/t Ag, 3.39% Zn.
  • MAP-104:
    • 5.35 m at 2.62 g/t Au, 2.61 g/t Ag, 1.04% Zn.
    • 0.5 m at 22.8 g/t Au, 13.95 g/t Ag, 0.52% Zn.
  • MAP-105:
    • 2.5 m at 3.3 g/t Au, 1.61 g/t Ag, 0.06% Zn.
    • 9.25 m at 1.77 g/t Au, 4.63 g/t Ag, 5.33% Zn.
    • 9.7 m at 0.17 g/t Au, 2.59 g/t Ag, 13.88% Zn, 0.91% copper (Cu).


MAP-101 was drilled well to the north of all previous drilling and angled away to a NW azimuth. The primary objective of the hole was to intersect and thus confirm the location of the northward continuation of the Aragon fault.

The hole was successful in these objectives, but no substantial mineralisation was intersected.


MAP-102 was drilled to test the northern extension of higher-grade mineralisation previously intersected in hole MAP-089. While substantial widths of mineralisation were intersected, these were of lower grade, and somewhat similar to the nearby hole MAP-097.


MAP-104 was drilled into a gap between the previously defined north and south sections of the APTA zone. This is a zone where the primary structures change direction and thus it was necessary to better define this section.

Some narrow high-grade gold and base metal veins were intersected.


MAP-103 and 105 were drilled to test the continuity of mineralisation previously intersected in MAP-098, but also to push downward to test stratigraphy to the limit of the available rigs. Both holes were drilled from the west, and so designed more as stratigraphic holes.

Reasonable intersections of gold mineralisation were intersected, however of most interest was the intersection in MAP-105 of a likely VMS system at depth with high grade zinc and copper mineralisation, including 5.95 m at 18% Zn and 1.4% Cu from 478 m.

Other drilling

As previously announced on 25 April 2022, drilling activities ceased at APTA in March, with the remaining rig mobilised to the northern Pepas prospect.

Extensive programmes of mapping, sampling and geophysics had been undertaken along the northern extent of the Aragon fault and associated structures over previous months, with highly anomalous geochemical and geophysical responses being recorded. Access to the area however was challenging due to terrain issues and substantial logistical infrastructure and support was required to be developed before rigs could be mobilised.

Drilling commenced at Pepas with one rig in April, with a second rig mobilised to Pepas in recent weeks. The company is also informed that a third rig has commenced drilling at Pupino, with a fourth in the process of being mobilised to commence at Pupino in the near term.

Core from the first hole at Pupino have been submitted to the laboratory for assay and results are expected soon.

Orosur CEO, Brad George, commented: “This last batch of holes were largely focused on resolving stratigraphic and structural issues at APTA, while waiting for permitting and access to be developed at the highly prospective northern prospects of Pepas and Pupino. APTA has been the focus of attention for Waymar, Orosur and Monte Águila since 2012 with the remaining 20 km of strike of the Aragon Fault tantalisingly out of reach. APTA proved the region is fertile, and field mapping in the north suggested this could continue, but it was only in April that we were finally able to move rigs onto these targets. We await with some anticipation the results of recent drilling at Pepas and Pupino and look forward to updating shareholders shortly.”

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