Impact vectors in on high-grade PGM at Broken Hill

ASX-listed PGM junior, Impact Minerals, has identified a “potentially powerful geochemical vector” that it says increases towards higher-grade nickel-copper-platinum group metals mineralisation at the Platinum Springs prospect which forms part of its Broken Hill project in NSW.

According to the Perth-based company, the vector points to two prospective mineralised corridors at Platinum Springs – where it is currently carrying out drilling – and represents a significant technical breakthrough in an area that has stumped many current and previous explorers over the years.

Impact claims the vector may offer a way to help overcome one of the main exploration stumbling blocks that both the company and its predecessors have had to contend with at Platinum Springs. Up until now, efforts to track and interpret the numerous high-grade drill intercepts spread over hundreds of metres along the Moorkai Trend have proved problematic.

The existence of a geochemical vector may hold the missing clue to more accurately refining target identification at the prospect.

The company suggests the missing piece to unlocking the mysteries at Platinum Springs has also discouraged extensive exploration over the whole Moorkai Trend, a 9km-long dyke and channel system that takes in Platinum Springs and which has yielded high-grade nickel-copper-PGM hits in rock chip samples along its entire length.

As part of its sleuth work in seeking to understand the nature and origin of the unusual ultramafic and mafic rocks that host the exceptional grades of nickel-copper-PGM mineralisation at the Broken Hill project, Impact came up with a multi-metal geochemical ratio that indicates a strong correlation with PGM grades and “offers a possible vector towards higher-grade zones”.

Impact says there appears to be a relationship between the geochemical ratio and PGM assay data from Platinum Springs, with anomalous values of more than 250ppb PGM generally associated with geochemical ratios of two to five and ratios greater than 10 likely showing PGM grades of more than 1 gram per tonne.

Incredibly, the ratio was calculated at well in excess of 10,000 from the narrow unit of magmatic nickel-copper-PGM sulphides that returned 0.6 metres grading 11.5 grams per tonne platinum, 25.6 g/t palladium, 1.4 g/t gold, 7.6 per cent copper, 7.4 per cent nickel and 44.3 g/t silver from 57.1m  down-hole.

Meanwhile, assay results have now been received for 10 holes of a 15-hole round of RC drilling at Platinum Springs. Impact pointed out that all the drill holes sit outside the corridors identified by its vector ratio and may therefore be outside the most prospective parts of the mineralised system.

Notable intercepts from Platinum Springs include 17m at 321ppb PGM from 42m down-hole including 1m at 610ppb PGM from 45m and 1m at 963ppb PGM from 57m, and 14m at 209ppb PGM from 41m including 1m at 541ppb PGM from 50m.

At Platinum West, notable intersections include 26m at 202ppb PGM from 97m including 1m at 725ppb PGM from 108m, 1m at 1,510ppb PGM from 111m, and 12m at 183ppb PGM from 96m including 1m at 829ppb PGM from 106m. While the values are not earth-shattering, they do confirm thick widths of modest-grade PGM occur over hundreds of metres in the project area.

The company is now planning further research on the nature of the vector and its applicability at Platinum Springs and other Broken Hill prospects.

There is some interesting work going on at Impact and it may be close to revealing the hidden truths at Platinum Springs. But for now, it is still a case of watch this space...

Is your ASX listed company doing something interesting? Contact: matt.birney@businessnews.com.au