en.Wedoany.com Reported - Porphyry deposits are among the most sought-after mineralization types globally, associated with hydrothermal activity from magma chambers kilometers beneath the deposit, and are renowned for their massive scale. This scale compensates for typically lower grades, with approximately 60% to 70% of global copper production, most molybdenum, and significant amounts of gold and silver originating from such deposits. Porphyry deposits are primarily distributed along the Pacific Ring of Fire, with key regions including Chile, the Caribbean, southern Central Europe, Turkey, China, Russia, and eastern Australia, typically forming in subduction zone settings. Representative mines include BHP's (ASX:BHP) Escondida mine in Chile, Rio Tinto's (ASX:RIO) Bingham Canyon mine in Utah, USA, and the Grasberg gold-copper mine in Central Papua.
Australia hosts a considerable number of porphyry deposits, most concentrated within the Macquarie Arc of the Lachlan Fold Belt in New South Wales. Notable deposits include Newmont's Cadia mine, Evolution Mining's (ASX:EVN) Northparkes mine, and Alkane Resources' (ASX:ALK) Boda-Kaiser project.
Mark Mitchell, Technical Director of Sultan Resources (ASX:SLZ), stated that two main porphyry mineralization types exist in the Lachlan Fold Belt: the Cadia type and the Boda type. Cadia has been mined since the mid-19th century, with large-scale operations beginning in the late 1990s; the Boda type was only discovered in 2019. Mitchell noted that hydrothermal breccia structures present in the Boda project are also found at Sultan's Star Plateau project, specifically the Razorback-Wattle Ridge anomaly zone. The skarn breccia exhibits unique textures, containing chalcopyrite accompanied by oxidized malachite-bearing skarn breccia, along with strong magnetic anomalies and corresponding IP chargeability anomalies. Outcrop rock samples show copper grades up to 2.65%, gold up to 2.25 g/t, low molybdenum content (consistent with Boda-type mineralization), and silver up to 9.2 g/t. Mitchell pointed out that previous operators drilled eastward rather than toward the magnetic anomaly zone to the west. He believes drilling should target the magnetic and IP anomaly directions, potentially pointing to the porphyry core, while elevated copper, gold, silver, and depleted molybdenum suggest the drilled area may be on the mineralization fringe.
Although this assessment pertains to Sultan's specific situation, it also reflects the view that many porphyry deposits remain to be discovered in the Lachlan Fold Belt, a sentiment shared by several other junior companies in the region. Sultan is planning next steps, with Mitchell recommending initial surface sampling to strengthen the model for Razorback-Wattle Ridge, the company's highest-ranked anomaly in the area. He also mentioned potential further work at Gowan Green (to the north), where outcrops, good copper grades, and gossan are present, but IP chargeability anomalies are lacking. Razorback-Wattle Ridge and Gowan Green are located at opposite ends of a 6 km by 1 km soil survey conducted in 2020 over the Big Hill porphyry prospect, which covers a northeast-trending magnetic ridge interpreted as part of the Molong Volcanic Belt.
Kincora Copper (ASX:KCC) operates a project covering structural and volcanic trends within the Macquarie Arc in the northern Junee-Narromine Belt, whose province-scale potential has attracted investment from AngloGold Ashanti. Exploration has upgraded direct targets, and drilling is underway.
Koonenberry Gold (ASX:KNB) holds 1,580 square kilometers in the region, with exploration at its Big Ben gold trend, Breakfast Creek, and Dunedoo projects within the Gundagai project including porphyry target testing. At Dunedoo, based on geological observations, alteration assemblages, and large-scale coincident geophysical anomalies, the company delineated a near-surface, drill-ready porphyry copper-gold prospect at Bolinda Vale. This includes a modeled 3D magnetic high body covering over 0.5 km by 0.3 km, interpreted as an underlying intrusive complex, associated with a large-scale IP anomaly measuring 1.6 km by 0.45 km, potentially representing the pyrite halo of a porphyry system. Zoned hydrothermal alteration is typical of Macquarie Arc porphyry systems. Meanwhile, its Junee joint venture partner Newmont has initiated a nine-hole drilling program to follow up on gold intersections at the Allawah prospect. The Junee project covers the southern section of the Junee-Narromine Volcanic Belt, the western zone of the Macquarie Arc, with work having delineated multiple near-surface discoveries, including porphyry gold-copper, porphyry copper-molybdenum, epithermal gold, and skarn mineralization systems.
Magmatic Resources (ASX:MAG) holds the Wellington North gold-copper project, surrounding the Boda-Kaiser project and covering the northern extension of the Molong Volcanic Belt. The project has intersected multiple copper-gold targets with grades comparable to Boda, including Boda Southwest and Rose Hill/Rose Hill North. Recent soil sampling at Boda Southwest, adjacent to Alkane's Boda 4 prospect, returned gold grades up to 4.7 g/t. Rose Hill and Rose Hill North have higher grades than Boda Kaiser, with previous drilling results including 71 meters at 0.43% copper, 0.3 g/t gold, and 57 ppm molybdenum. The company also owns the Myall project, targeting Northparkes-type pencil porphyry copper-gold deposits, with multiple targets identified sharing similar characteristics. Drilling at Myall has yielded several intersections with grades approaching those of Northparkes. Early 2026 drilling results, funded by Fortescue, intersected 7 meters at 0.19% copper from 223 meters, and 10 meters at 0.15% copper, extending the Corvette-Kingswood mineralization system at the Interceptor prospect 1 kilometer south. Further drilling assay results from this project are pending.
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