Pampa Medina Is About to Get a Number: What the Delineation Data Says About the Floor

Project Overview

Pampa Medina is a manto-type copper deposit held by Marimaca Copper (TSX: MARI | ASX: MC2), located approximately 28 kilometres east of the Marimaca Oxide Deposit (MOD). The deposit is hosted in Jurassic-Triassic sedimentary units, comprising sandstones, conglomerates, tuffs, and black shales, with multiple stacked mineralised horizons positioned beneath andesitic volcanics and above an Upper Palaeozoic complex.

Marimaca Copper is currently executing a delineation campaign across Pampa Medina's defined area of interest on a 150-metre by 150-metre grid spacing, with a maiden Mineral Resource Estimate (MRE) as the programme's primary objective. The deposit is characterised by a deeper sulphide system dominated by bornite and chalcocite, while shallow oxide mineralisation is viewed by the company as a complementary, open-pittable satellite resource.

1. The Spacing Reduction: 300m to 150m

The reduction from 300-metre scout and step-out holes to a 150-metre by 150-metre delineation grid marks the formal transition from exploration to resource definition at Pampa Medina, and the dataset being generated is the direct input to the maiden MRE compilation.

Marimaca Copper designates the current work explicitly as a delineation campaign, structured to define the high-grade central area of interest before returning to broader step-out exploration. The MRE process is being guided by an independent resource geologist.

2. Programme Scale & the Area of Interest

The defined area of interest at Pampa Medina covers 3 kilometres by 1.5 kilometres, within a campaign targeting approximately 35,000 metres of drilling, establishing the geographic boundary from which the maiden MRE will be drawn.

The high-grade core within that area extends 1.5 kilometres north to south and 600 to 800 metres east to west. Beyond the immediate area of focus, an identified mineralised trend extends 3 to 4 kilometres to the north, with step-out testing to follow once the delineation phase closes.

3. Delineation Intercepts: Grade & Width Performance

A 96-metre sulphide envelope grading 1.19% copper and 11.7 grams per tonne (g/t) silver from 692 metres depth confirms that the 150-metre delineation grid is capturing ultra-high-grade mineralisation at the widths and depths the deposit geometry predicts.

The most significant sub-intervals narrow sharply in width: 16 metres at 5.70% copper and 62.6 g/t silver from 704 metres, including 4 metres at 11.32% copper and 144.0 g/t silver from 706 metres. A 60-metre interval at 1.80% copper and 18.4 g/t silver from 694 metres bridges the broader sulphide envelope to the higher-grade core. Shallow oxide mineralisation is also present, including 22 metres at 0.40% copper from 60 metres and 24 metres at 0.30% copper from 204 metres.

A second delineation hole returned 22 metres of sulphide at 1.97% copper and 9.2 g/t silver from 610 metres. It also intersected a shallower mixed zone of 140 metres at 0.35% copper from 366 metres, including stacked manto intervals: 32 metres at 0.71% copper and 4.1 g/t silver from 468 metres, and 10 metres at 0.95% copper and 7.4 g/t silver from 484 metres.

4. Grade Continuity Across the High-Grade Corridor

The intercept record across Pampa Medina's high-grade corridor demonstrates systematic rather than episodic grade delivery: 96% of drill holes have returned intercepts exceeding 10 copper percent-metres, and 58% have exceeded 20 copper percent-metres.

With the exception of two holes, every hole in the delineation grid has returned economic widths and grades, with mineralised package thickness reaching up to 26 metres in individual zones. That compares with a 4.5-metre average at the Kupferschiefer deposit, a sediment-hosted copper system that management has cited as a structural analogue to Pampa Medina. 

Chief Executive Officer of Marimaca Copper, Hayden Locke, places the programme's grade delivery against that benchmark:

"Every drill hole that we drill, bar two, basically has been mineralised over what we perceive to be economic widths and grades. Some of them are absolutely exceptional, and some of them are just good. But if you compare us to the [Kupferschiefer], which we have a lot of analogous items in comparison to, we're drilling and delivering grades and widths that are exceeding the [Kupferschiefer] deposits in every single drill hole, so that adds up very quickly."

5. The Inferred Classification Threshold

The independent resource geologist has indicated that 150-metre by 150-metre spacing is expected to qualify for Inferred classification once the delineation grid is complete, based on observed conditions within the programme rather than a continuity model imported from another deposit.

High-grade sulphide mantos are showing strong lateral continuity across the defined area of interest, with delineation holes continuing to intersect high grades over significant widths. The maiden MRE is targeted to carry an Inferred classification, establishing the deposit's first categorised resource statement from the current delineation dataset.

6. Timeline to the Maiden MRE

The data cutoff for Pampa Medina's maiden MRE triggers immediately upon completion of the 150-metre delineation campaign, with the drill programme targeted for completion in September 2026.

A six to seven-month resource compilation period follows the cutoff, placing maiden MRE delivery in 2027. The initial resource will not capture the full extent of the mineralisation delineated by the programme.

Locke outlined the timeline from drill completion to maiden MRE delivery:

"That's about another 35,000 metres of drilling in this current campaign, which will be done by the end of September. And then we'll take six to seven months to put together an initial resource. That initial resource will be over a very small snapshot of what we think we've delineated. It's not going to be everything, but it'll be something that allows people to start looking at it and going, okay, this is actually a real, real opportunity."

7. Post-MRE Development Scenarios

The optimal development path for the sulphide system remains unresolved, with scenario analyses to be conducted only after the maiden MRE establishes Pampa Medina's classification scale. Post-cutoff drilling will shift to broader step-out testing of distal northern and western extensions, running in parallel with the resource compilation period.

Bornite and chalcocite, the dominant copper species in the deeper sulphide system, are both leachable, placing an extended leaching operation among the development paths that scenario analysis will evaluate. The shallow oxide component offers a separate development path, with the potential to add approximately 25,000 tonnes per year to the MOD's cathode output and to extend the district's mine life. 

Locke connects the mineralogy to the system's processing optionality:

"One of the more interesting things that I'm taking away from the sulphide opportunity at Pampa Medina is the dominant mineral species. The copper species are bornite and chalcocite, both of which are leachable, so there is a world where those become part of a really extended leaching operation, and we expand our eventual cathode production significantly. There will almost certainly be a concentrator portion, but look, we're at an early stage, we've got to deliver the resource first."

Key Takeaway for Investors

• The 150-metre delineation grid has replaced step-out drilling as the operative programme at Pampa Medina, and the dataset it is generating serves as the evidence base for the maiden Mineral Resource Estimate compilation.
• The defined area of interest covers 3 kilometres by 1.5 kilometres, with a high-grade core extending 1.5 kilometres north to south and 600 to 800 metres east to west, within a campaign targeting approximately 35,000 metres of drilling.
• Intercept consistency across the high-grade corridor, with 96% of holes exceeding 10 copper percent-metres and 58% exceeding 20 copper percent-metres, supports the deposit's grade performance as systematic rather than episodic.
• The independent resource geologist has indicated that a completed 150-metre by 150-metre grid is expected to support Inferred classification at Pampa Medina.
• The data cutoff triggers upon completion of the September 2026 campaign, with a six to seven-month compilation period placing maiden Mineral Resource Estimate delivery in 2027.
• The sulphide system's bornite and chalcocite mineralogy offers potential for an extended leaching operation, and the shallow oxide satellite could add approximately 25,000 tonnes per year to the Marimaca Oxide Deposit's cathode output, with development scenarios to follow the Mineral Resource Estimate.

Bottom Line

The delineation data assembled to date at Pampa Medina establishes a credible floor on what the maiden MRE will show. Grade-thickness composites above 10 copper percent-metres in 96% of holes, ultra-high-grade intercepts within a defined area of interest, and an independent resource geologist's indication that the completed 150-metre grid is expected to support Inferred classification constitute the evidence base from which the deposit's first classified number will be drawn. With the data cutoff set for September 2026 and maiden MRE delivery targeted in 2027, the current programme is not exploration. It is a resource construction.