Impact Minerals Limited (ASX: IPT) announced that stand out drill intercept of 138 metres at 0.3 g/t 3PGE (palladium+platinum+gold) including 12 metres at 1.5 g/t 3PGE, 0.3% nickel, and 0.2% copper was returned from the Red Hill prospect within its Broken Hill nickel-copper-PGM project in New South Wales.
The company said that this was the first significant indication of nickel-copper-PGM mineralisation within the Red Hill intrusion and the intercept is open at depth.
IPT said that a further nine out of 11 other drill holes into the margin of the Red Hill intrusion also returned strongly anomalous and significant 3PGE+/-copper+/-nickel in zones between four and 33 metres thick.
The company said that the new drill result at Red Hill complements the break through drill results delivered at the Platinum Springs and Rockwell-Little Broken Hill Gabbro prospects during its 2020 drill campaign. IPT said that a second major drill programme is now being planned to follow up all of these highly prospective areas.
Drill programme at Broken Hill
Impact had completed 15 RC drill holes at Red Hill prospect for 2,408 metres in its 2020 drill programme. The company said that a further 3 RC drill holes for 622 metres were also completed at the adjacent Dora East silver-lead-zinc target with final assays awaited.
Outstanding drill results from Red Hill
The company said that significant intercepts were returned from drill holes at the Red Hill prospect including a stand out drill intercept from hole RHIPT034, which was drilled to test a soil geochemistry anomaly along the southern contact of the Red Hill chonolith.
Hole RHIPT034 returned 138 metres at 0.3 g/t 3PGM (Pd+Pt+Au) from surface which includes several higher-grade intercepts of 2 metres at 2.3 g/t 3PGE from 75 metres, and 12 metres at 1.5 g/t 3PGM and 0.2% copper from 103 metres which includes 2 metres at 2.3 g/t 3PGM, 0.3% copper and 0.3% nickel from 109 metres, and also includes 2 metres at 1.1 g/t 3PGM and 0.2% copper from 135 metres.
The company said that this result has demonstrated that the chonolith-shaped (tube-like) ultramafic intrusion at the Red Hill body hosts significant thicknesses of disseminated PGM+/-copper+/-nickel mineralisation close to surface. The company noted that the intercept is open at depth and this is a priority target area for follow up drilling.
Strongly anomalous intercepts of 3PGM
The company said that the review of all 12 drill holes that have penetrated the margin of the Red Hill chonolith (8 drill holes from the 2020 drill campaign and 4 from previous campaigns) indciated that ten of them contained strongly anomalous intercepts of 3PGM, with variable copper and nickel, within about 30 metres of the contact with the surrounding rocks.
All of this mineralisation occurs in the so-called “chilled margin” of the intrusion where the parental magma of the chonolith first cooled as it intruded into the surrounding rock.
Intercepts in the chilled margin
Five of the other intercepts in the chilled margin from the 2020 drill programme included RHIPT030 – 33 metres at 0.2 g/t 3PGM including 7 metres at 0.5 g/t 3PGM and 0.3% copper from110 metres which includes 1 metre at 0.6 g/t 3PGM and 0.45% copper from 112 metres; RHIPT027 – 17 metres at 0.3 g/t 3PGM from 2 metres down hole including 2 metres at 1.2 g/t 3PGM and 0.2% copper from 8 metres down hole; RHIPT028 – 10 metres at 0.3 g/t 3PGM from 23 metres including 4 metres at 0.6 g/t 3PGE and 0.2% copper from 26 metres; RHIPT033 – 4 metres at 0.4 g/t 3PGM from 105 metres; and RHIPT035 – 14 metres at 0.4 g/t 3PGM from 80 metres.
Follow up drilling planned
IPT said that the recent work by the CSIRO has shown that chonoliths with mineralised chilled margins have a strong chance of hosting significant massive sulphide deposits either at the base of the intrusion, in “throttle-zones” or in shallow dipping parts of the intrusion. The company said that the deeper part of the Red Hill intrusion beneath the new stand-out drill intercept is therefore a compelling priority target for follow up drilling.
An analogy to the Red Hill target included the Eagle (4.6 Mt at 3.7% Ni and 3% Cu) and related Eagle East (1.2 Mt at 5.1% Ni and 4.3% Cu) chonoliths of the Mid-Continent Rift in North America (Lundin Mining).
The company said that Red Hill drilling will be incorporated into a major drill programme being designed to also follow up the breakthrough drill results that Impact has recently returned at the Platinum Springs and Little Broken Hill Gabbro prospects. Final assays from these two prospects are due within a few weeks.
The company said that a large amount of new data was generated from the extensive drill programme completed at Broken Hill in 2020 and a detailed synthesis and interpretation of the data in context is in progress in order to prioritise the targets for the follow up drilling.
IPT said that the drilling will resume at Broken Hill as soon as practicable and discussions are in progress with drilling contractors to determine timing and cost.
Impact said that work is also on-going planning the maiden drill programme at its Apsley porphyry copper-gold target. The company said that the final data from the ground Induced Polarisation survey has now been received and a detailed interpretation is in progress.