Australian exploration company Castillo Copper (ASX:CCZ) has sent a geology team to assess 3 prospects at the NWQ Copper Project in Queensland.
The company says the geology team will be visiting the Big One, Arya, and Valparaisa prospects in the first half of 2023 to identify new targets for drill testing.
At the Big One prospect, some areas were drill tested in the 2020 and 2021 drilling campaigns, however much of this area remains underexplored.
Utilising information from Castillo’s drilling campaigns, complemented with historical data, Castillo’s geological consultant compiled an ‘extensive’ database, built a block model, and produced a maiden Mineral Resource Estimate (MRE) of 2.1 million tonnes @ 1.1% copper (Cu) for 21,886 tonnes of copper metal.
Building on this work, Castillo’s geology team believe further drilling is warranted along the known orebody to the east, north, and down-dip as it is not fully defined.
Furthermore, the geology team believes a well-designed drilling campaign focused on diamond drilling has the potential to materially increase the grade and confidence in the current MRE as the orebody is open to the east and down dip.
Additionally, the company reports an exploration target has been estimated utilising the MRE plus some areas proximal to, and down-dip to the main resource shell, as well as available geophysics and surface sampling data.
Castillo says the exploration target’s mid-range is 4 million tonnes @ 0.6% to 1% Cu, with the low at 2Mt, and the high at 6Mt.
Commenting on the geology team site visit, Castillo Copper Managing Director Dr Dennis Jensen says: “With the macro-outlook for copper remaining upbeat, the board has authorised the geology team to visit several prospects to identify new targets to drill test. Key areas of focus include increasing the grade and confidence in the current MRE at Big One and the magnetic anomaly at the Arya Prospect.
“With the macro-outlook for copper remaining upbeat, the board has authorised the geology team to visit several prospects to identify new targets to drill test”
Given the large size of the NWQ Copper Project, the board remains open to aligning with a strategic partner to further advance development work.”
Castillo reports the Valparaisa Prospect comprises copper mineralisation in 2 horizons known as the upper and lower copper beds within the Middle Gunpowder Creek Formation over a 6km strike length. The company says the lower bed has a ‘stronger’ outcrop and more copper staining compared to the upper bed.
Previous explorers undertook rock chip sampling which returned ‘high-grade’ assay results up to 2,530 parts per million (ppm) Cu, which Castillo says demonstrates prospectivity at surface for copper mineralisation. It also notes the surface anomalism aligns with the intersection of the Mt Gordon fault (southwest to northeast, links to the Mt Mammoth Deposit) and Valparaisa fault (south-southeast to north-northwest).
Based on reconciling and interpreting the surface anomalisms, Castillo believes there is a structurally controlled copper system at Valparaisa. As further evidence, the company identified the Whitworth Quartzite rock formation within the Valparaisa fault. This formation hosts copper sulphide mineralisation within the Mt Gordon fault, and the Mt Mammoth deposit.
At the Arya Prospect, Castillo reports a limited drilling campaign was carried out in late 2021 to test several large airborne electromagnetic and ground resistivity anomalies. This drilling confirmed a ‘low-grade’ graphite system that will not be further explored.
However, the company says a ‘sizeable’ magnetic anomaly south of the known electromagnetic anomalies is interpreted to be associated with known surface copper and silver mineralisation.
Castillo says a key focus of the site visit is to determine if this should be drill tested as it may be a primary source of base metal mineralisation at Arya. The company believes the mineralisation styles at Arya include supergene mineralisation forming at the surface along the fault, fault breccia, and the Surprise Creek Formation rock unit, and epigenetic replacement mineralisation for copper from replacement carbonate mineralisation.
Other suggested mineralisation styles include skarn mineralisation from replacement carbonate mineralisation, as well as sulphide mineralisation within the breccia zones along stress dilation fractures, placed within pore spaces, voids, or in other rock fractures and dykes.
Castillo Copper is an Australian explorer focused on copper across Australia, and Zambia. The company holds a portfolio of assets including a large footprint in the Mt Isa copper belt district in northwest Queensland, 4 ‘high-quality’ prospective assets across Zambia’s copper belt, a large tenure footprint near the Broken Hill deposit in New South Wales, as well as the Cangai Copper Mine in northern New South Wales.
Images: Castillo Copper Ltd
