Sentinel Metals (ASX: SNM) Hits 46.8 Metres at 5.5 g/t Gold at Columbia

Sentinel Metals has reported a broad, high-grade gold intercept from the first hole of its maiden drilling program at Columbia in Montana.

Diamond hole DDCO26-001 returned 46.8 metres at 5.5 grams per tonne gold from 88.2 metres. That interval included 21.4 metres at 11.1 grams per tonne from 97.6 metres. It also contained 13.5 metres at 16.6 grams per tonne from 105.5 metres.

The result tests known mineralisation beneath Columbia’s historical oxide zone. However, low core recovery within the highest-grade section creates an important qualification around the preliminary grades.

High-Grade Oxide Intercept

The 46.8-metre composite recorded 72% core recovery and sits within oxidised material. Its high-grade core returned 21.4 metres at 11.1 grams per tonne, with 49% recovery.

Recovery fell to 20% across the 13.5-metre interval grading 16.6 grams per tonne. It ranged between 12% and 62% within that section.

Sentinel said low recovery was not systematically associated with grade enrichment elsewhere in the hole. Five comparable low-recovery intervals returned gold at or below detection limits. Still, the company said sampling bias cannot be discounted and the reported grades should be treated as indicative.

The interval will be re-drilled using triple-tube equipment. Sentinel has already adopted that drilling method to improve recovery as the program advances.

Gold Extends Into Fresh Rock

Gold was also encountered below the redox boundary, around 135 metres down-hole. Four fresh-rock intervals extended mineralisation to 218 metres, with core recovery between 95% and 100%.

These included 17.1 metres at 0.4 grams per tonne from 142.9 metres. A further 14.5 metres graded 0.8 grams per tonne from 183.5 metres.

This matters because historical operators generally targeted oxide material suitable for heap-leach feed. They typically did not drill deeply into fresh rock at Columbia. The new hole therefore provides initial evidence that the mineralised system continues beneath the oxide blanket at this location.

Further drilling is required to determine continuity, geometry and grade in the fresh sulphide domain. No metallurgical testing has been completed on fresh sulphide material.

Resource Context and Caveats

Columbia hosts an inferred Mineral Resource of 21.4 million tonnes at 1.3 grams per tonne gold. That estimate contains 920,000 ounces of gold and was reported above a 0.4865 grams per tonne cut-off.

DDCO26-001 was drilled down-dip through the existing resource. All reported intervals are down-hole lengths, while true widths remain unknown.

The gold results were produced using PhotonAssay and remain preliminary. Fire-assay checks were expected around August 15 to 17, and the grades may be revised.

Meanwhile, the deeper hydrothermal breccia between 288 and 330.1 metres returned only 0.04 grams per tonne gold. That result was classified as sub-economic at this location.

Upcoming Results

Sentinel is completing a 21-hole maiden program of about 5,000 metres. Assays for holes DDCO26-002 through DDCO26-005 are pending.

The company plans follow-up drilling across the fresh sulphide horizon. Silver, multi-element and umpire laboratory analyses also remain outstanding for the first hole.