Sentinel Metals has reported broad, stacked gold mineralisation at its Columbia project in Montana, including a 48-metre intercept at 1.13g/t gold. Fire assays have also confirmed the company’s earlier high-grade maiden-hole result, while a November resource update now looms as the key test.
- 48m at 1.13g/t gold in DDCO26-003
- High-grade core of 1.5m at 12.1g/t gold
- Fire assays confirm 46.8m at 5.33g/t gold in DDCO26-001
- Deepest hole returned no significant gold but added geological data
- Updated Columbia resource estimate targeted for November
Stacked Gold Zones Strengthen Columbia Drilling Case
Sentinel Metals Limited (ASX:SNM) has added a substantial near-surface intercept to its Columbia gold-silver story, with DDCO26-003 returning 48 metres at 1.13g/t gold across multiple stacked zones. The result included 6.1 metres at 3.50g/t, including 1.5 metres at 12.1g/t, and extended through roughly 140 metres of down-hole mineralisation from 18 metres.
The hole also delivered 17.8 metres at 1.00g/t from 39.1 metres and 17.5 metres at 0.82g/t from 60.5 metres. Deeper mineralisation remained evident below the oxide zone, including 2.5 metres at 2.59g/t from 123 metres and 2.5 metres at 1.64g/t from 157 metres. All reported intervals are down-hole lengths; true widths have not yet been established.
Fire Assays Validate Maiden Hole Result
Fire assays have also confirmed the standout result from DDCO26-001, with 46.8 metres at 5.33g/t gold from 88.2 metres. That interval contains 21.4 metres at 10.6g/t and a 13.5-metre high-grade section at 15.7g/t, broadly reconciling with the earlier PhotonAssay results.
The confirmation is useful because the high-grade section had very poor core recovery, averaging about 20%. The company said the two assay methods reconciled within 3% to 6% through the high-grade zone, while a peak sample returned 41.3g/t by fire assay against 40.7g/t by PhotonAssay. Fire-assay data will be used in the planned resource update.
Shallow Mineralisation Offset by Deep Hole Failure
DDCO26-004 returned gold from its first sampled interval, including 7 metres at 0.82g/t from 12 metres and 5.7 metres at 1.34g/t from 45 metres. The latter included 2.6 metres at 2.55g/t. However, recovery through parts of the shallow oxide zone was low, ranging from 51% to 79% across the reported intercepts, leaving some sampling uncertainty.
The picture was less encouraging at depth. DDCO26-002, a 700.8-metre test of a conductive target identified by the 2025 HSAMT survey, returned no significant gold, with a peak assay of 0.19g/t. Sentinel said the hole nevertheless supplied the deepest geological information collected at Columbia and has been incorporated into the geological model.
November Resource Update Becomes the Next Test
The 2026 program is the first drilling at Columbia in about 20 years and is designed to test continuity beneath and beside the existing 920,000-ounce inferred JORC 2012 resource. Drilling is scheduled to finish in early October, with assays from holes DDCO26-005 to DDCO26-007 expected during October and an updated Mineral Resource Estimate targeted for November.
That update will need to convert encouraging intercepts into a coherent geological and grade model rather than simply count headline metres. The pending silver and multi-element assays, uncertain true widths and variable recovery - particularly in oxide material - will all influence how much of the drilling translates into additional reported resources.
Bottom Line?
The drilling has improved the evidence for shallow and stacked gold at Columbia, but the November resource estimate will determine whether those results amount to meaningful resource growth.
Questions in the middle?
- How much of the reported down-hole mineralisation will translate into true-width resource extensions?
- Will low recovery in oxide intervals affect the confidence or classification of any resource increase?
- Can the remaining assays and pending silver results support a materially larger Columbia resource in November?