Sentinel Metals Ltd (ASX:SNM, FRA:QN5) has delivered a strong start to maiden diamond drilling at the Columbia Gold-Silver Project in Montana, USA, intersecting 46.8 metres at 5.5 g/t gold from 88.2 metres, including a high-grade core of 13.5 metres at 16.6 g/t gold from 105.5 metres.
The first hole, DDCO26-001, also returned 21.4 metres at 11.1 g/t gold from 97.6 metres, while drilling confirmed that gold mineralisation continues beneath the historically targeted oxide zone into fresh rock.
Gold was encountered in fresh rock over four discrete intervals extending to 218 metres down-hole, with core recovery of 95%-100% in this zone. Further drilling will be required to determine the continuity, geometry and grade of mineralisation within the fresh sulphide domain.
Maiden hole highlights potential below oxide zone
Additional intersections from DDCO26-001 included 17.3 metres at 1.1 g/t gold from 88.2 metres and 16 metres at 1.0 g/t from 119 metres, with core recoveries of 88% and 99%, respectively.
Further down-hole, drilling returned 17.1 metres at 0.4 g/t gold from 142.9 metres, 8.2 metres at 0.7 g/t from 170 metres and 14.5 metres at 0.8 g/t from 183.5 metres.
Managing director Matt Herbert said the first hole had both delivered a strong maiden intercept and confirmed gold continued into fresh rock below the oxide blanket, an area historically not typically drilled as previous operators focused on oxide material suitable for heap leaching.
The company has since moved to triple-tube drilling to improve core recovery as the program progresses.
Core recovery prompts further verification
Sentinel cautioned that core recovery within the highest-grade 105.5-119.0-metre interval averaged only 20%, ranging from 12% to 62%.
While the company said its analysis had not identified a systematic relationship between lower recovery and higher grades, sampling bias cannot be ruled out and the reported grades in the low-recovery interval should be regarded as indicative. Sentinel plans to re-drill the interval using triple-tube equipment.
The gold results were generated using PhotonAssay and are preliminary, with fire-assay check analyses pending.
Columbia Gold-Silver Project
Columbia is an epithermal gold-silver system in Lewis & Clark County, Montana, comprising patented and unpatented mining claims held through Sentinel's wholly owned Great Plains Mining LLC.
The project hosts an inferred mineral resource of 21.4 million tonnes at 1.3 g/t gold and 4.6 g/t silver, containing around 920,000 ounces of gold and 3.14 million ounces of silver, or 960,000 ounces on a gold-equivalent basis.
The maiden program is designed to test deeper structural zones, down-dip extensions of known mineralised veins and previously undrilled geophysical targets.
Next steps
Sentinel is progressing its current 21-hole maiden drilling program, with assays from DDCO26-002 through DDCO26-005 pending.
The company also intends to follow up the fresh sulphide horizon between the redox boundary and about 218 metres, while completing silver and multi-element analyses and additional laboratory checks on DDCO26-001.
Follow-up drilling of the deeper 288-330-metre hydrothermal breccia has been deprioritised after assays returned a length-weighted 0.04 g/t gold, although Sentinel's deeper conceptual porphyry-style target remains untested.
About Sentinel Metals
Sentinel Metals is focused on the Columbia Gold-Silver Project in Montana. Its current drilling program is aimed at testing extensions to known mineralisation as well as deeper structural and geophysical targets around the existing Columbia mineral resource.