Auroch Minerals Ltd (ASX:AOU) (FRA:T59) has intersected nickel sulphide mineralisation along strike in a maiden reverse circulation (RC) program at the high-grade Nepean Nickel Project south of Coolgardie, Western Australia.
The regional RC and aircore programs were designed as a first-pass reconnaissance test of several magnetic high anomalies which extend along 10 kilometres of strike from the historic high-grade Nepean nickel mine.
Encouraging results include:
- 4 metres at 0.49% nickel from 25 metres, cut off at depth by a pegmatite vein;
- 7 metres at 0.33% nickel from 86 metres, sitting on the basalt footwall contact and with a coincident localised DHEM conductor;
- 39 metres at 0.44% nickel from 19 metres, with a coincident localised DHEM conductor; and
- 1-metre at 0.60% nickel from 67 metres, the last 1-metre sample at the end of an aircore hole which represents the top of competent fresh rock.
“Very promising signs”
Managing director Aidan Platel said that while the company was in the early exploration phase, he was thrilled to see very promising signs that Auroch was potentially homing in on new nickel sulphide discoveries at Nepean.
He said: “Due to the distinct lack of historical drilling, our conceptual exploration target was based almost purely on the 10-kilometre of strike of aeromagnetic anomalies extending from the historic Nepean nickel mine, and hence our first phase of drilling was to test this theory.
“The program has been a huge success, with the drill-holes identifying thick sequences of high MgO fertile ultramafic units overlying a footwall basalt, the perfect setting for Kambalda-style nickel sulphide mineralisation.”
Testing aeromagnetic anomalies
Seventeen drill holes for 2,374 metres of the recently completed 32-hole RC program were drilled to test high-order aeromagnetic anomalies along the 10 kilometres of anomalous strike extending from the historic Nepean nickel mine.
In parallel, 31 aircore holes for 1,110 metres were completed to test several more subtle magnetic features and to provide early-stage stratigraphic information.
The northern section of the Nepean strike has never been tested, with the bulk of historic drilling focusing on the mineralisation at the Nepean mine itself and on some minor gold occurrences to the south.
Presence of thick zones of elevated nickel values builds on the fertility of the system and demonstrates the company is one step closer to a potential nickel sulphide discovery.
Background nickel values for an ultramafic rock are typically up to 0.30% nickel, and therefore assays above that in fresh rock, along with elevated sulphur values, are indicative that there are nickel sulphides present.
While the reported intervals are subeconomic, they are encouraging as they confirm a fertile nickeliferous ultramafic system that could potentially host massive nickel sulphide mineralisation.
Kambalda-style nickel deposits
Platel continued: “Several thick zones of elevated nickel were intersected to confirm the disseminated sulphides logged by our geologists in the field, which is extremely encouraging.
“In other words, we know that we have nickel sulphide mineralisation present in the right geological setting along strike from the historic Nepean nickel mine, and now it is a case of building on this information to vector in on the potential massive nickel sulphide “channel” mineralisation that is typical of Kambalda-style nickel deposits.”
He said a high-powered ground MLEM survey is underway at Nepean and is expected to add further targets for drill testing.