AFR ARTICLE-read and weep , y'allTapping the Pilbara’s gold...

AFR ARTICLE-read and weep , y'all
Tapping the Pilbara’s gold potential
Global gold production is on track to hit an all-time high in 2023 and, with previously overlooked deposits in Australia now being uncovered, that may not be the peak for long.The World Gold Council predicts this year’s output will likely surpass the previous record of 3656 tonnes set in 2018 after a record total of 2460 tonnes was produced in the first half of the year.Its Gold Demand Trends Q2 2023 report states while Australian production fell 2 per cent year-on-year in the quarter, a 7 percent increase occurred globally.“Mine production reached 923 tonnes – an all-time second-quarter high in our records,” it says. “Although it is too early to be certain, our expectation, based on Metals Focus data, is that the trends in the first half of the year suggest mine production will hit a new all-time high in 2023.”Australia was the world’s third-largest gold producer in 2022, the council’s annual figures show. The output of 313.9 tonnes was less than that of China (375 tonnes) and the Russian Federation (324.7 tonnes).Most of Australia’s gold is mined in Western Australia, and mostly in Kalgoorlie.However, gold was first discovered further north in the state, in the Kimberley and the Pilbara regions in the 1880s – a decade before the possible existence of iron ore in those areas was first noted.Almost 150 years later, the rediscovery of gold in a Pilbara area is further cementing Western Australia as the nation’s gold state.De Grey Mining’s Hemi gold discovery, about 60 kilometres south of Port Hedland, is estimated at 10.6 million ounces, and is in an area previously not believed to contain the precious metal.However, Mantle Minerals chief executive Nick Poll says the region has been under-tested for minerals such as gold and believes it is on the cusp of finding a similar amount to Hemi.He says overlooking the gold deposit was an easy miss for previous explorers to make.“There have been sniffs of gold in the Pilbara for maybe 20 years but they didn’t find the big one at Hemi until a couple of years ago – and that’s largely because of these covering rocks that can be up to 35 metres thick,” Poll says.“On our tenements, the geophysical signature from these covering sediments is much worse than over Hemi.“Our geophysics appears like a sea of nothing, so it’s easy to assume there’s nothing there.“But the Hemi mineralisation system is a giant,’’ he adds, ‘‘and we think there’s a good chance it extends well onto our ground because we have already intersected gold mineralisation associated with arsenic, a key indicator of mineralisation at Hemi.”Poll says that De Grey also encountered similar mineralisation grades before making its big discovery.“The Pilbara is one of the greatest iron ore regions of the world and if you compare it to another great iron ore region, Carajas, we should expect to see more discoveries of major deposits such as copper, nickel and, of course, gold,’’ he says. “We don’t fully understand why the Carajas region is so well endowed with these world-class deposits but a lack of understanding shouldn’t stop us from assuming the Pilbara region has similar potential.
“The Hemi discovery provides definitive proof that the Pilbara region has so much more potential, particularly where potential deposits are concealed.”Mantle Minerals has returned to its Robert’s Hill tenement, located alongside De Grey’s Hemi deposit, to focus on gold after exploring for nickel at its nearby Pardoo tenement. Poll says an announcement on heritage approval and drilling commencement is imminent.“My experience from 35 years in gold, nickel and copper exploration is you need to look for evidence of large mantle-tapping structures if you want to find the big deposits,” he says.“I joined the company and renamed it Mantle Minerals because I believe we already have the evidence of such a mantle-tapping system at Hemi next door; we just need to prove it extends on to our ground. One of the key indicators we have is arsenic and gold occurring together, from some of the drilling that we carried out [at Robert’s Hill] a couple of years ago.”Poll says that it also is not considered to be a typical exploration situation when compared to that in Kalgoorlie.“In the Kalgoorlie region, a halo of remobilised gold often provides very clear vectors to primary mineralisation,” he says. “But we don’t seem to have that advantage in our area.“It seems gold has been leached, so any indication of primary mineralisation, even if it’s low grade, means a lot more than it would in the Kalgoorlie region.“We have to be much more persistent once we have discovered primary mineralisation with the right mix of indicators.“That means we need to keep drilling over broad areas to make sure we’re focusing on the best targets and we need to tighten the drill-hole spacing and drill deeper around any significant intersections.”Poll says the company thinks the best target is gold hosted in mafic rocks, which may occur on its tenement, so that will be the focus of the next drilling round.“It’s not a surprise that nobody has been able to find these gold deposits until recently, given the covering sediments, lack of halos to target primary mineralisation and poor response to geophysics,” he says. “While that can be frustrating, it’s also our opportunity, because we have the benefit of knowing we are in the right place and just need to persist