Latest assays from ongoing drilling at prospects within Peel Mining’s (ASX: PEX) South Cobar project in western New South Wales have returned a host of high-grade copper intervals including the company’s widest copper intercept to date.
The widest intercept to date was at the Wirlong target and returned 205m at 1.4% copper and 3 grams per tonne silver from 434m.
Drilling at the Wirlong and Mallee Bull targets continues to define a growing copper system where the mineralisation remains open in most directions.
The maiden program at Wirlong was designed to test the upper part of the Wirlong Central zone, where high-grade copper (chalcopyrite) mineralisation is structurally controlled on a northwest-southeast orientation locally known as the John Owen Fault.
The mineralisation is also interpreted to be influenced by the interaction between the John Owen Fault and the regional scale north-south trending Woorara Fault, creating what Peel described to be a “sinistral strike slip fault zone encompassing en echelon vein arrays”.
The first hole drilled at Wirlong hit the 205m intercept and contained many higher grade intervals such as 161m at 1.53% copper and 3g/t silver from 434m, including 7m at 3.63% copper and 7g/t silver from 458m, 9m at 3.19% copper and 9g/t silver from 475m, 11m at 4.32% copper and 8g/t silver from 501m and 10m at 4.6% copper and 7g/t silver from 584m.
Other Wirlong holes were recognised as hosting significant copper mineralisation, with best assays of 21m at 1.31% copper and 6g/t silver from 336m, including 6m at 2.2% copper and 9g/t silver from 337m; 22m at 1.36% copper and 4g/t silver from 256m, including 5m at 2.91% copper and 10g/t silver from 260m, and 2m at 3.69% copper and 12g/t silver from 274m; and 13m at 2.2% copper and 10g/t silver from 315m, including 5m at 4.35% copper and 14g/t silver from 319m.
Peel estimated the true width of intercepts associated with the John Owen Fault to be up to 60% of the downhole widths, while the true width of mineralisation distal to the Fault is more variable depending on vein array orientations relative to the respective drill hole.
The undeveloped Mallee Bull target is believed to be one of Australia’s highest-grade copper deposits, with a 2017 resource estimate of 6.76Mt at 1.8% copper, 31g/t silver, 0.4g/t gold, 0.6% lead and 0.6% zinc (2.6% copper equivalent) for approximately 119,000t of copper, 6.6 million ounces silver, 83,000oz gold, 38,000t lead and 38,000t zinc (using a 1% copper equivalent cut-off grade).
Although the mineralisation commences 60m below surface and has been defined to at least 800m below surface (remaining open along strike and at depth), the bulk of the target’s contained copper is located from 350m below surface, where the resources are predominantly of an inferred nature.
The resource upgrade program at Mallee Bull comprises approximately 20,000m of diamond drilling and is designed to convert inferred resources to the indicated category.
Two double shifting multi-purpose rigs have so far drilled 80% of the schedule, while a recent review highlighted the potential to optimise the resource upgrade outcome by modifying the drilling program.
Better results from Mallee Bull to date are: 21m at 2.03% copper and 38g/t silver from 319m; 8.27m at 3.62% copper and 23g/t silver from 311m; 62m at 2.14% copper and 15g/t silver from 324m; and 36m at 3.55% copper and 72g/t silver from 345m.