Lodestar Validates Concealed IOCG System With Cobalt-Rich Skarn Intercept in Chile
Key Takeaways
- Drill hole L3SDD004, completed to 611.10m, confirms a positive correlation between iron content and sulphide mineralisation consistent with an IOCG hydrothermal system — validating the geological model across two holes for the first time in the Three Saints area's history.
- The skarn intercept near end-of-hole returned anomalous copper and cobalt values peaking at 1,314 ppm Cu and 404 ppm Co, providing a new vector pointing toward potentially more favourable host rocks.
- Best intercepts include 14.82m at 483 ppm Cu and 97 ppm Co (0.10% CuEq) from 404.40m, with a 1m high-grade sub-interval hitting 2,901 ppm Cu and 120 ppm Co (0.43% CuEq) at 407m.
- The presence of carbonatic fluids — which cannot originate from the tonalite host rock — indicates possible proximity to a volcano-sedimentary basin, a key targeting insight for the next drill program.
- Three Saints now sits within a three-project Chilean copper portfolio alongside Los Loros (five new porphyry targets identified in May 2026) and the newly acquired Pacífico Cu-Mo-Au Porphyry Project, giving Lodestar multiple exploration catalysts in a tier-one jurisdiction.
Lodestar drilling confirms IOCG model at Three Saints copper project in Chile
Lodestar Minerals Limited has received final assay results for its second diamond drill hole at the Three Saints IOCG Project in Chile’s Atacama region — and the data validates the geological model management has been chasing. The hole, L3SDD004, drilled to 611.10m, confirms a positive correlation between iron content and the presence of sulphides, consistent with an IOCG (Iron Oxide Copper Gold) hydrothermal mineral assemblage. The assays also delivered anomalous copper and cobalt values in a skarn intercept, providing a significant new vector for exploration targeting.
What this tells you: two holes have now confirmed a concealed IOCG-style hydrothermal system beneath extensive cover. L3SRD003 and L3SDD004 are the first drill holes historically known in the Three Saints area. The company has converted a geophysical anomaly into a validated hydrothermal system with defined vectors — a material de-risking step for an early-stage exploration play.
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What the L3SDD004 assays revealed
The geochemical response in L3SDD004 aligns with zones of sulphide mineralisation and hydrothermal alteration identified during geological logging. Copper-sulphides are linked to magnetite-bearing mineralisation, associated with the main actinolite-biotite and sodic-calcic (skarn) hydrothermal alteration within the tonalite intrusive. The assays confirm sulphide mineralisation (pyrite-chalcopyrite) spatially associated with magnetite veins and breccias and biotite-actinolite alteration, locally accompanied by albite and scapolite.
The hydrothermal breccia intercepted close to the end of hole — between 568m and 570.26m — yielded anomalous high values of copper and cobalt (maximum 1,314 ppm Cu and 404 ppm Co). This mineralisation is related to fine sulphide dissemination within strong sodic-calcic alteration of garnet and epidote (retrograde) within the tonalite intrusive. The presence of carbonatic fluids — which cannot be provided by the tonalite host rock — could indicate proximity to a volcano-sedimentary basin, a key targeting insight.
Significant intercepts
| Interval (From–To) | Width (m) | Cu (ppm) | Co (ppm) | CuEq % |
|---|---|---|---|---|
| 221.0m – 223.0m | 2.00 | 1,064 | 86 | 0.14% |
| 333.0m – 337.3m | 4.30 | 765 | 75 | 0.12% |
| Including: 333.0m – 334.42m | 1.42 | 2,020 | 78 | 0.25% |
| 404.40m – 419.22m | 14.82 | 483 | 97 | 0.10% |
| Including: 407.0m – 408.0m | 1.00 | 2,901 | 120 | 0.43% |
| 568.0m – 572.0m (skarn) | 4.00 | 359 | 256 | 0.15% |
| 598.0m – 600.0m | 2.00 | 165 | 272 | 0.13% |
All intervals are downhole length; true width is not known. CuEq formula: Cu % + Mo % x 6.321 + Au g/t x 1.000 + Co % x 4.040. Metal prices and recovery assumptions are detailed in Appendix 1 of the source announcement.
A CEO callout on the geological breakthrough
Coraline Blaud, CEO & Executive Director
“The Three Saints drilling program has delivered an encouraging geological outcome, identifying a previously untested, concealed IOCG-style hydrothermal system. The first two drill holes confirmed copper-gold mineralisation and a strong alteration assemblage consistent with an IOCG system. Importantly, the second hole intersected skarn alteration accompanied by cobalt mineralisation, providing an important geological vector towards potentially more favourable host rocks.”
Understanding IOCG deposits — and why this matters
An IOCG deposit is a copper-gold system where mineralisation is tied to iron oxide (magnetite) and specific hydrothermal alteration. Think magnetite + sulphides (chalcopyrite, pyrite) + actinolite-biotite and sodic-calcic (skarn) alteration. That is the signature package. Confirming the IOCG model de-risks the geological interpretation and tells the company where to hunt next.
Three Saints sits in Chile’s Coastal Cordillera IOCG belt, a recognised copper region that includes the Candelaria, Punta del Cobre, and Mantoverde deposits. The regional comparison is for geological context only and does not imply that Three Saints has comparable mineralisation, scale, grade, resources, or economic potential.
Key IOCG signatures found in the drill core:
- Magnetite association: Copper-bearing sulphides spatially linked to magnetite veins and breccias
- Sulphide mineralisation: Pyrite-chalcopyrite occurring as fracture infill and dissemination
- Alteration assemblage: Actinolite-biotite and sodic-calcic (skarn) alteration within tonalite intrusive
- Cobalt enrichment: Anomalous Co values related to iron hydrothermal injection, particularly in skarn zones
The investment angle — from concept to targeting
Two holes have now confirmed a concealed IOCG system beneath extensive cover, converting a geophysical anomaly into a validated hydrothermal system with defined vectors. The Fe-Co rich, lower Cu signature to the east indicates proximity to a feeder structure — a targeting clue. In IOCG deposits, Fe-bearing minerals precipitate at high temperatures early in the hydrothermal cycle; copper precipitates later, at lower temperatures. The distribution tells you where the plumbing sits.
Three Saints sits within Lodestar’s broader Chilean copper portfolio alongside the Los Loros porphyry project and the newly acquired Pacífico Cu-Mo-Au Porphyry Project. The portfolio positioning gives the company multiple shots on goal in a tier-one jurisdiction, with Three Saints now advancing from geophysical concept to drill-validated system.
Los Loros update and the wider Chilean portfolio
The Los Loros drilling program has been postponed due to El Niño weather events that damaged access roads in Chile’s northern regions, preventing the safe passage of heavy machinery. The government is currently undertaking repairs to public road infrastructure. Drilling will commence once access has been reinstated.
Los Loros remains highly prospective. In May 2026, Lodestar identified five new copper and gold targets at the Águila prospect following IP+MT and Magnetometry surveys, confirming potential for a fully preserved, close-to-surface porphyry system with targets from 150m to 800m depth.
Lodestar’s Chilean copper portfolio now comprises:
- Three Saints IOCG Project: Drill-validated IOCG system with confirmed copper-gold-cobalt mineralisation and defined exploration vectors
- Los Loros Porphyry Project: Five new copper-gold targets identified; drilling postponed pending road repairs
- Pacífico Cu-Mo-Au Porphyry Project: Strategic low-cost entry into a potentially large-scale copper system
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What comes next at Three Saints
The next phase focuses on reprocessing, reinterpreting, and calibrating existing geophysical datasets using the newly defined alteration and mineralisation signatures as geological constraints. The goal: extend mineralised structures laterally and at depth to intersect feeder structures within the most mineralisation-receptive volcano-sedimentary units.
Planned further work:
- Detailed re-logging of L3SRD003, integrating assay results with geological interpretation
- Integration of L3SDD004 assays with structural and alteration data
- Reprocessing and reinterpretation of magnetometry surveys to refine structural control and identify prospective hydrothermal corridors
- Integrated geological-geochemical-geophysical targeting to prioritise next drill targets
The recurring association between copper-bearing sulphides, magnetite, and actinolite-biotite and skarn hydrothermal alterations provides an important vector for refining the interpretation of the structural architecture of the Three Saints system. The company now has a clearer understanding of the system and the geological controls that will guide the next phase of exploration.
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