Impact Minerals (ASX: IPT) has confirmed new high-grade assays for platinum group elements (PGEs) with associated copper and nickel have significantly expanded the mineralised footprint at the Plat Central and Plat East prospects, which form part of its wholly-owned Broken Hill project in New South Wales.
The assays were taken from numerous basal channels discovered along the ultramafic-to-mafic Moorkai trend, which is a poorly-explored 9km-long dyke and chonolith complex hosting the larger Platinum Springs area.
At Plat Central, high-grade mineralisation was identified in extension to the basal channel with best results being 36m at 0.7 grams per tonne of gold-palladium-platinum (3PGE) from 3m, including 3m at 5.4g/t 3PGE, 0.9% copper and 1.5% nickel from 76m, which includes 1m at 10.3g/t 3PGE, 2.3% copper, 3.3% nickel, 88g/t silver and 711 parts per million cobalt.
The discovery of a second basal channel, which may merge with the first, also contained good grades of mineralisation such as 5m at 1.3g/t 3PGE, 0.2% copper and 3% nickel from 65m, including 1m at 2g/t 3PGE, 0.5% copper and 0.4% nickel; and 1m at 4.6g/t 3PGE, 0.2% copper and 0.8% nickel.
A further new channel was discovered at the poorly-drilled Plat East prospect, with a highlight of 27m at 0.5g/t 3PGE from 22m, including 3m at 2.7g/t 3PGE, 0.4% copper and 0.5% nickel from 41m, which includes 1m at 4.7g/t 3PGE, 0.6% copper and 1.1% nickel from 42m.
Mineralisation was also identified for the first time within the host ultramafic unit well above the basal channel, which – together with numerous thick intercepts of lower grade mineralisation throughout the ultramafic – supports the potential for a larger bulk mining opportunity.
Best results were 13m at 1.9g/t 3PGE, 0.5% copper and 0.4% nickel from 9m including 2m at 6.7g/t 3PGE, 2% copper and 1.1% nickel from 19m, which includes 1m at 8.5g/t 3PGE, 3% copper and 1.4% nickel.
Impact said mineralisation at Platinum Springs has now been defined over 1,000m of trend but with significant gaps of up to 250m, which are still untested.
Follow up work programs are scheduled to commence once maiden drilling at the Apsley porphyry copper-gold prospect has been completed.
Impact managing director Dr Mike Jones said the company is beginning to identify the nature of the unique mineralisation within the Platinum Springs area.
“Our 2020 drill program was [our] first systematic drill campaign in the area and delivered exceptional assay results and very significant breakthroughs in our understanding of the mineralisation,” he said.
“The results defined significant PGE-copper-nickel mineralisation over 1,000m of trend from Plat East to Plat West across the Platinum Springs area and with considerable gaps of up to 250mof that trend that remain undrilled.”
Dr Jones said it remains “highly likely” that numerous Kambalda-style basal channels remain to be discovered along the Moorkai trend.
“The basal channels at the world-class Kambalda nickel mining district have a ribbon-like geometry… they are mostly less than 7m thick, generally up to 100m wide, but usually extend for many hundreds of metres to kilometres along the trend of the channel,” he said.
“The channels we have discovered at Platinum Springs are about the same thickness but are not as wide as those at Kambalda and have only been tracked along about 150m of trend.
“The challenge now is how to track the channels along trend to areas where they are larger and more continuous,” Dr Jones said.