Copper-gold exploration on a district scale in Argentina’s Vicuña Belt

Peñas Negras project area, La Rioja, Argentina.

Sendero Resources is advancing Peñas Negras in La Rioja Province, Argentina. Its contiguous land position brings together established mineralization, multiple exploration areas and the potential for concealed porphyry and epithermal systems.

The project covers 211.77 km², comprising 120 km² that is 100% owned and approximately 91.7 km² of adjoining concessions under an option to earn a 100% interest.

Explore the historical drilling results

September 23, 2026 | Historical drilling review

Broad mineralized intervals across Peñas Negras

Sendero reviewed 77 historical drillholes and 6,433 assay samples. Sendero applied a consistent CuEq methodology across the historical database.

Selected recalculated historical results

Intervals are downhole lengths; true widths are unknown. CuEq includes copper, gold, silver, molybdenum, lead and zinc, using respective prices of US$4.50/lb, US$3,375/oz, US$60/oz, US$25/lb, US$1,440/t and US$2,940/t. Recoveries of 100% are illustrative; actual recoveries may differ.

View full historical drill results

A significant land position in the Vicuña Belt

Peñas Negras lies within the Andean copper-gold district that hosts Filo del Sol, Josemaría and Lunahuasi, alongside the producing Caserones copper mine.

Sendero’s target area is approximately 12 km north-northeast of the Josemaría resource area. Measured from the centre of the Peñas Negras concession area, Caserones lies approximately 18 km to the northwest, Lunahuasi 24 km to the southwest and Filo del Sol 32 km to the south-southwest.

Regional setting of Peñas Negras.

These neighbouring deposits provide regional geological context. Their mineralization and economic characteristics are not necessarily indicative of those at Peñas Negras.

Peñas Negras lies within the Miocene Andean magmatic arc. Exploration has identified mineralized drill intervals, widespread hydrothermal alteration, multiple intrusive phases and structural corridors that Sendero considers consistent with a large porphyry and epithermal mineral system.

The Company has integrated drilling, geological mapping, surface geochemistry, geophysics and alteration data to understand how these features relate across the property and at depth.

The Mogotes Fault and associated structures are central to this interpretation because they may have provided pathways for mineralizing fluids. Sendero’s exploration strategy focuses on testing these structural controls and the potential for concealed copper-gold mineralization.

Peñas Negras district geology and exploration target areas. Source: Sendero Resources, August 17, 2026.

2026 reconnaissance drilling and surface sampling

The 2026 reconnaissance program completed three diamond drillholes totalling 396.3 m, together with 453 rock samples collected across the property.

All three holes returned near-surface gold and silver mineralization. Hole PNDH-201 returned 1.5 m grading 1.04 g/t gold and 48 g/t silver from 14 m, within a broader interval extending from surface to 46 m and averaging 0.11 g/t gold. True widths are unknown.

Drilling identified an extensive leached cap, while PNDH-203 confirmed the presence of the Mogotes Fault and returned anomalous antimony. These observations add structural and geochemical evidence supporting the Company’s exploration model.

Surface sampling returned values of up to 4.82 g/t gold and 18 g/t silver in an area approximately 9 km from the reconnaissance drilling. These are individual sample results and do not establish average grades or mineralized continuity across the property.

Read the August 2026 exploration update

Fieldwork at Peñas Negras.

Sendero’s exploration strategy evaluates priority areas along a nine-kilometre exploration trend, testing the project’s district-scale potential and investigating structural controls on mineralization. The trend describes prospective areas, rather than established mineralized continuity.

The Company’s work focuses on the hydrothermal system associated with the Mogotes structural corridor and the additional areas identified through surface geochemistry. Approximately 3 km of the prospective Mogotes corridor remained untested in the August 2026 update.

Historical drill results

Au = gold; Ag = silver; Cu = copper; Mo = molybdenum; Zn = zinc; Pb = lead. ppm = parts per million.

Intervals are downhole lengths; true widths are unknown. CuEq includes copper, gold, silver, molybdenum, lead and zinc, using respective prices of US$4.50/lb, US$3,375/oz, US$60/oz, US$25/lb, US$1,440/t and US$2,940/t. Recoveries of 100% are illustrative; actual recoveries may differ.

View full results and methodology in the September 23, 2026 news release.

Technical sources

Sendero Resources Rebuilds Peñas Negras Drill Assay Database, Applying Consistent CuEq Methodology Across 77 Historical Holes (September 23, 2026).

Sendero Resources Reports Drilling Results at Peñas Negras Project; Confirms Geological Model and Identifies Geochemical Vectors in Vicuña Belt, Argentina (August 17, 2026).

Sendero Resources: Geological model and exploration targets (Feb 17, 2026)

Sendero Resources: Interim CEO appointment and exploration strategy (Sep 8, 2026)