Dart Mining has kicked off geophysical surveying at its Granite Flat porphyry copper-gold target in north-eastern Victoria. The company is now knee-deep in magneto-telluric and induced polarisation surveys that measure both magnetic and electrical responses, respectively, within underlying rocks, highlighting the mineralised geology and potentially lighting up insitu sulphide mineralisation.
The current work program is designed to test an area about 2km long and 4km wide, which extends across the core of an interpreted copper-gold porphyry target. Previous drilling at Granite Flat has returned some impressive results, including 19 metres at 9.39 grams per tonne gold, 19.2 g/t silver and 0.61 per cent copper from only 28m down-hole, providing a taste of the potential metal endowment of the underlying porphyry intrusive complex.
Porphyry deposits are coveted by mining companies for the rich endowment of gold and base metals they can host. Porphyries account for the bulk of copper production across the globe.
Large, low-grade porphyry ore systems typically occur within recognised provinces across the world, with some of the most famous deposits occurring around the Pacific Rim, including BHP’s colossal Escondida mine in northern Chile and Newcrest’s flagship Cadia mine on the Lachlan Fold Belt in central New South Wales.
Granite Flat is situated on the southern extensions to the Lachlan Fold Belt, a terrane that has also produced a rash of more recent porphyry discoveries. These discoveries include Alkane’s Boda deposit, just north of Orange in NSW, which catapulted the company’s share price from 38c in late 2019 to $1.48 12 months later as the market recognised the potential value of the discovery.
The Granite Flat porphyry target lies around 20km south-east of Eskdale in north-east Victoria and forms part of Dart’s extensive Mitta Mitta project area. The company has already outlined an extensive surface geochemical anomaly at the prospect that stretches over more than 3km of strike and has produced sample hits of up to 0.45 per cent copper and 4.7 g/t gold in the outcropping rocks and soils.
Subsequent wide-spaced drilling over the core of the Granite Flat anomaly has intersected a number of high-grade gold hits with the majority of the shallow drill holes from the program recording anomalous grades of copper, gold and silver.
Importantly, many of the shallow drill holes at Granite Flat ended in anomalous copper-gold mineralisation, suggesting a potential treasure trove of metal mineralisation in the deeper roots of the porphyry target. This deeper potential has prompted the company to undertake the current geophysical surveys, which will allow Dart to see through the vegetation and soil cover and better target future drilling.
With Dart ticking all the boxes in its bid to identify a large porphyry target at Granite Flat its next drilling program could be the litmus test for a company looking for Australia’s next major copper-gold discovery.
Is your ASX-listed company doing something interesting? Contact: email@example.com