A mining company based in Broken Hill has announced that it has created a novel method for accessing a geological deformation that has been shielding a valuable mineral deposit.
This deposit, identified over four decades ago, is believed to host potentially millions of tonnes of sought-after minerals. The company asserts that accurate drilling results could secure its future in mining for years to come.
The mineral deposit was initially uncovered in 1983 beneath the streets of an outback mining city, situated close to current mining operations. This area was named the “Centenary Zone” in honor of the city’s 100th anniversary, and the original mine operator held high hopes for the resources beneath but faced significant challenges in accessing them.
Patrick Walta, the executive chair of Broken Hill Mines, which acquired the site in 2024, explained that the previous operator had drilled about 13 holes exceeding a kilometre in depth to reach the deposit.
“They successfully intersected the Centenary lode, which was estimated to contain around 5 million tonnes, with a zinc equivalent grade of eight to nine percent,” he noted. “However, they encountered a geological barrier known as the Glove-Vauxhall Shear, which disrupted access.”
Geologist Sandra Close characterized the shear zone as a natural rock deformation that presents significant drilling challenges. “The rocks in this area have been crushed and pulverized into a thick layer, making drilling extremely difficult,” Dr. Close explained. “Attempts to drill through this zone often result in drill rods becoming stuck, preventing any thorough testing for the last 43 years.”
This largely unexplored lode may soon see activity after more than four decades. Mr. Walta mentioned that the geology team at Broken Hill Mines has devised an innovative approach for targeted drilling beyond the shear zone.
“They accomplished this by drilling a wide-diameter hole through the shear and casing it, which enabled the insertion of narrower daughter holes,” Mr. Walta elaborated. “This method allowed us to penetrate the shear efficiently and assess the true nature of the Centenary Zone.”
Recent drilling indicates that the deposit may be approximately five times thicker than previously anticipated and exhibits nearly double the expected purity of zinc, a crucial anti-corrosive mineral used worldwide to protect metals like steel from rust.
“It is evident that the resource will significantly exceed the current estimate of five million tonnes. If we can increase the drilling to 10, 15, or even 20-plus million tonnes, it would have substantial implications for our operations,” Mr. Walta stated. “This would also ensure a long-term feed supply for our existing plant, facilitating extended mining activities in Broken Hill.”
Dr. Close expressed admiration for the geology team’s innovative solution to access the Centenary Zone, expressing optimism about the company’s long-term goals. However, she cautioned that it is premature to confirm success, noting that the exploration will require considerable investment.
“The real challenge will be how they navigate the difficult terrain within the shear, enabling the necessary equipment to access the area and develop ventilation shafts,” Dr. Close remarked. “While their approach is certainly groundbreaking, there remains much work ahead.”
