Cobre has logged copper sulphide mineralisation in its first deep diamond hole at Sierra Atacama since 2021, extending the system below the existing operation. The result is encouraging but remains visual and preliminary, with laboratory assays due in October.
- 986.9m diamond hole tests mineralisation below existing operation
- 3.57m and 0.60m visual sulphide intervals logged
- Estimated chalcopyrite abundance of up to 6%
- 11 reverse circulation holes completed and four rigs operating
- Assays expected in October during 40,000m campaign
Deep hole extends Sierra Atacama mineralisation
Cobre Limited (ASX:CBE) has taken its first deep look beneath the Sierra Atacama operation since 2021, drilling to 986.9 metres and logging copper-bearing sulphides in previously untested ground. The hole indicates that the mineralising structures continue at depth, although the company has not yet produced laboratory grades or true-width measurements.
Hole SA_CBR_DD001 contains a 3.57-metre downhole interval from 784.90 metres with estimated visual abundances of 4% chalcopyrite and 2% pyrite. A second 0.60-metre interval from 798.20 metres carried estimated abundances of 6% chalcopyrite and 3% pyrite. Together, the intervals total 4.17 metres within a nearly kilometre-long hole and are hosted by magnetite-rich hydrothermal breccias.
Assays will determine the economic weight
That distinction matters. The reported figures come from geological logging and visual estimates, not assays, and Cobre explicitly cautions that visual abundance is not a substitute for laboratory analysis. The reported lengths are downhole intersections rather than true widths, while the announcement states that a single hole is insufficient to establish geological or grade continuity. Assay results are expected in October.
The geology nonetheless adds another layer to the project’s exploration story. The hole passed from shallower oxide and supergene mineralisation into magnetite-cemented breccias containing chalcopyrite, pyrite, actinolite and quartz. Cobre also highlighted mineralised sedimentary units as potential hosts for manto-style deposits, raising the possibility of more than one mineralisation style within the broader system. That remains a geological interpretation rather than a defined resource.
Four rigs advance the resource drilling programme
The deep hole is one part of a planned 40,000-metre surface and underground programme intended to validate historical drilling, add infill data, test brownfields targets and probe below the current mine. Cobre said 11 reverse circulation holes have been completed, underground drilling has begun around the high-grade mixed zone at the base of the current operation, and additional diamond drilling is targeting extensions beneath northern underground workings.
Chief executive Adam Wooldridge said the result confirmed the scale of the mineralising system below the existing operation and described the sedimentary host rocks as offering potential for thicker manto-style mineralisation. He also said four rigs were operating as the company works towards converting its NI 43-101 resource into a maiden JORC-compliant estimate while ramping up production. The next test is whether the assays support the visual logging and whether subsequent holes show enough thickness, grade and continuity to affect the resource model.
Bottom Line?
October assays are the immediate catalyst, but the larger question is whether one deep intersection can be repeated across the 40,000m programme with economic grades and usable widths.
Questions in the middle?
- Will laboratory assays confirm meaningful copper grades in the two visually logged intervals?
- Can follow-up drilling demonstrate continuity beyond this single deep hole?
- How will the new deep and underground results change the maiden JORC resource timeline and scale?