Soil sampling at the Briggs porphyry copper-molybdenum project in Queensland confirms upside with a large anomaly now measuring 2,300m long and up to 1,000m wide at >500ppm copper.

Even more exciting, Alma Metals (ASX:ALM) says within the >500ppm copper anomaly are several clusters of >1,000ppm copper which reflect the known mineralised centres at Briggs Central, the Northern porphyry and southern porphyry target.

In addition to anomalous copper, the soil sampling has highlighted anomalous molybdenum up to 84ppm Mo, which is associated with the porphyry system.

The molybdenum anomaly is not perfectly co-incident with copper anomalism and ALM believes this could be an indication of a polyphase/zoned intrusive system at Briggs, as confirmed from core logging.


Drilling to kick off shortly

Alma plans to resume drilling shortly, targeting potential extensions of the mineralisation to validate a revised exploration target, which sits at 480Mt to 880Mt at 0.20% to 0.30% Cu and 25ppm to 40ppm Mo.

The soil sampling over the Briggs porphyry copper system also showed that the currently defined Inferred Resource closely correlates to drill-tested areas where copper is greater than 500ppm in the soils.

With that in mind, another goal in the next round of drilling is to assess higher-grade zones within the recently published mineral resource estimate (MRE), which comprises an Inferred Resource of 415Mt at 0.25% copper and 31ppm Mo at 0.20% Cu cut-off.

Since the copper mineralisation extends well into the volcanic sediments surrounding the intrusions – at least 150m in some cases – Alma reckons that the Northern Porphyry, Briggs Central and Southern Porphyry centres may therefore coalesce into a single, large mineralised system with further drilling.


Next steps

A program of approximately 2,500m in eleven diamond drill holes has been planned, which includes four holes between the Northern Porphyry and Briggs Central to partly validate the exploration target, and seven holes to test higher grade zones in Briggs Central.



This article was developed in collaboration with Alma Metals, a Stockhead advertiser at the time of publishing.


This article does not constitute financial product advice. You should consider obtaining independent advice before making any financial decisions.