Inca Minerals (ASX:ICG) thinks it could potentially have a big “Tier 1” deposit on its hands in Queensland following a review of past rock chip sampling that showed high-grades and the hallmarks of a “porphyry” system.

The world’s largest, most profitable copper mines are open pit porphyry deposits and enable a project to be developed as a low to mid‐cost operator over a very long potential mine life.

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The normally Latin America-focused explorer says historical rock chip sampling done at the MaCauley Creek project indicated grades of up to 8.44 per cent copper, 720 grams per tonne (g/t) silver, 2.35 per cent zinc and 11.7 per cent lead.

As a rule of thumb, high grades are anything above 6 per cent copper, 50g/t silver, 12 per cent zinc and 10 per cent lead.

READ: Here’s a plain language guide on how miners ‘grade’ mineral discoveries

But besides the high-grades, Inca says MaCauley Creek, which lies within the Townsville-Mornington Island mineral belt, features strong copper, silver and molybdenum mineralisation in granite — a characteristic of porphyry-style mineralisation.

The project, which Inca only added to its portfolio last month, sits in a region that hosts over 20 porphyry deposits and/or prospects in the region.

Inca came to the conclusion that previous exploration conducted at MaCauley Creek “strongly supports the concept of a possible porphyry”.

The news lifted shares over 33 per cent to 0.4c on Tuesday morning.


In other ASX base metals news today:

Orion Minerals (ASX:ORN) has pinpointed a number of ways it can lower the costs of development of its flagship Prieska copper and zinc project in South Africa.

“We identified numerous opportunities to improve on the Foundation Phase mining plan during the feasibility study process,” managing director Errol Smart told investors. “In our opinion, these opportunities can result in quantum improvements in the already pleasing project financial returns and risk profile.”

One area Orion thinks it can reduce costs is water treatment and mine dewatering. Orion says field trials currently underway have the “potential to materially reduce project capital costs”.