Sentinel Metals Hits 21.7m at 2.19g/t Gold and Extends Columbia Beyond Pit Shell
Key Takeaways
- Hole DDCO26-011 returned 21.7m at 2.19g/t Au from just 36m, including 9.0m at 4.31g/t, with 99% core recovery on the headline zone.
- DDCO26-010 hit 9.1m at 2.56g/t Au, including 2.0m at 9.44g/t, outside the current pit shell, the primary target of the resource update.
- Results are in for 11 of 15 holes across about 3,700m of drilling, with the final four assays due in the coming weeks.
- The updated Columbia Mineral Resource Estimate is targeted for November 2026, building on the existing 920,000oz Inferred Resource at 1.3g/t Au.
- Southern holes returned lower grades and narrower widths, and the failed survey tool in DDCO26-011 means a re-survey is needed before the estimate is finalised.
Northern drilling extends Columbia mineralisation beyond the pit shell
Sentinel Metals (ASX: SNM) has reported that hole DDCO26-011 returned 21.7m @ 2.19g/t Au from 36m, including 9.0m @ 4.31g/t Au, at its Columbia Gold-Silver Project in Montana, USA. Hole DDCO26-010 returned 9.1m @ 2.56g/t Au, including 2.0m @ 9.44g/t Au, outside the current Mineral Resource pit shell.
Results are now in for 11 of the 15 holes completed in the 2026 program, with assays pending for the final four. Drilling concluded on 2 October 2026, covering approximately 3,700m, and all results will feed the updated Columbia Mineral Resource Estimate targeted for November 2026.
These are the latest results from the company’s maiden drill program. The existing Inferred Mineral Resource at Columbia stands at 21.4Mt @ 1.3g/t Au for 920,000oz of gold. All results reported are preliminary PhotonAssay, pending fire assay confirmation.
Matt Herbert, Managing Director
“…Results have now been received from 11 of the 15 holes completed in the 2026 drilling program, providing a substantial dataset ahead of the November Mineral Resource Estimate update.”
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Hole-by-hole results
DDCO26-011 delivers the best intercept
DDCO26-011 was collared in the northern part of the current resource area, approximately 200m west of DDCO26-001. The headline 21.7m @ 2.19g/t Au intercept had 99% core recovery, and includes a single 1.5m sample of 20.75g/t Au.
A second zone of 21.3m @ 1.18g/t Au from 205.2m (91% recovery) lies within the lower part of the pit shell. A final 9.5m @ 0.64g/t Au from 237.0m lies outside the shell and extends to within 2.5m of the end of the hole.
In total, the hole returned 73.3m above 0.3g/t Au averaging 1.44g/t Au. Note that the hole’s survey tool failed, which matters for how firmly the geometry can be read (more on that below).
DDCO26-010 steps out
DDCO26-010 was collared about 90m north-east of DDCO26-011. Its outside-shell intercept had 77% core recovery, and mineralisation remains open down-dip.
In total the hole returned 38.3m averaging 1.46g/t Au, of which 13.7m averaging 1.83g/t Au lies outside the shell. One caution: an interval of 2.8m @ 3.02g/t Au was recovered at only 33% and should be treated with caution. Results for the final 4.6m of the hole have not yet been received.
| Hole | Key intercept | Position vs pit shell | Core recovery | Total mineralised metres |
|---|---|---|---|---|
| DDCO26-011 | 21.7m @ 2.19g/t Au from 36.00m | Within and outside shell | 99% | 73.3m |
| DDCO26-010 | 9.1m @ 2.56g/t Au from 138.5m | Within and outside shell | 77% | 38.3m |
| DDCO26-009 | 3.0m @ 0.80g/t Au from 123.5m | Within shell | 100% | 34.5m |
DDCO26-009, collared 65m south of DDCO26-001 within the resource, is included for contrast. It returned multiple lower-grade zones, all at 100% recovery.
Southern holes show lower grades
DDCO26-005 to DDCO26-008 tested the southern end of the deposit, outside the footprint of the pit shell. The best result was 3.2m @ 1.56g/t Au from 6.4m in DDCO26-005, while DDCO26-007 returned no significant intercept above the 0.3g/t Au cut-off.
The company noted that gold continues south of the shell at lower grade and narrower widths than in the north. These holes will inform the resource update.
Why does the pit shell matter for the resource update?
A Mineral Resource Estimate is a formal calculation of how much mineralisation a deposit contains, and at what grade. A pit shell is an economic boundary, modelled here at a gold price of US$2,200/oz, that constrains the current Mineral Resource.
Mineralisation outside that boundary is, in the company’s words, the “primary target of the resource update”. The announcement does not state whether the resource will grow, or by how much, and exploration results are not Mineral Resources.
For you as an investor, three things stand out:
- Broad, shallow mineralisation has been confirmed in the northern part of the resource area.
- Drilling has intersected mineralisation beyond the limits of the current pit shell.
- A larger dataset will support the refreshed estimate.
Sentinel also holds the Big Springs Gold Project in Nevada, which hosts a Mineral Resource of more than 1 million ounces.
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What are the next steps to the November MRE?
Drilling achieved its key objectives of testing the existing geological model and areas beyond the current pit shell. The company lists these upcoming milestones:
- PhotonAssay results for DDCO26-012 to DDCO26-015, expected in the coming weeks.
- Fire assays and silver/multi-element results for DDCO26-005 to DDCO26-015.
- An updated Columbia Mineral Resource Estimate incorporating all 2026 drilling, targeted for November 2026.
- Planning of the 2027 drilling program.
There are some caveats to weigh. The survey tool failed in DDCO26-011, and the hole will be re-surveyed before the Mineral Resource update. True widths have not yet been determined and are expected to be less than the downhole lengths reported, and no metal equivalent is reported.
What this tells you is that the next few weeks carry the news flow. Remaining PhotonAssay results, followed by fire assay confirmation, lead into the November resource update, which is the event that will show how these northern results are reflected in the estimate.
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