American Pacific Mining has announced assay results from its underground sampling at the Madison Copper-Gold Project in Montana, US.
The sampling included investigations of a recently identified breccia pipe and the historic mine’s decline ramp.
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The company had earlier highlighted the identification of a breccia-hosted zone linked to a deeper porphyry source.
Current assays confirm the presence of mineralisation within this system, supporting the interpretation of a feeder system.
The upcoming second-quarter drilling campaign will further explore this feeder system’s down-plunge extent.
High concentrations of copper reaching 25%, gold up to 3.19 grams per tonne (g/t) and silver up to 27.2g/t were recorded from the underground sampling.
The assessment mapped approximately 150m of a continuous mineralised zone.
The breccia pipe exhibited intense alteration with both sulphide and oxide mineralisation, while sampling along the decline ramp showed extended mineralisation beyond the pipe, correlating with structural zones and conducive host rocks.
Observations included disseminated to semi-massive sulphides, suggesting fluid migration along the underground corridor.
These findings strengthen the interpretation of a continuous mineralised system, with the breccia pipe serving as a primary fluid conduit and the decline ramp indicating fluid dispersion.
Seasonal groundwater level reduction permitted access to previously flooded segments, offering new geological insights.
Future steps include incorporating these results into a 3D geological model, refining drill angles, and advancing a reverse circulation and diamond drilling programme to target various depths of porphyry mineralisation.
American Pacific Mining exploration managing director Eric Saderholm said: “While we expected to see mineralisation in samples collected from the breccia underground, the copper grades we sampled were better than we anticipated.
“What surprised us even more were the strong gold and copper values we found outside the breccia, along the main underground access. This tells us the mineralising system is larger than we thought and extends to the south and west, giving us clearer drill targets for 2026 as we test the potential porphyry source at depth.”
