Castillo Copper Limited (ASX: CCZ) has announced a highly positive update from the comprehensive review of historic data for the Big One Deposit and Boomerang Mine within the Mt Oxide pillar in Mt Isa’s copper-belt in QLD.
CCZ reported that it has secured original logs/assay results for then listed, West Australian Metals’ 27-hole (1,673m) RC drilling campaign at the Big One Deposit (Mt Oxide pillar) which had excellent economic copper intercepts up to 28.4% Cu.
The company announced that once approvals are secured, the Big One Deposit will be prioritised for drill-testing along with the Boomerang Mine and Arya Prospect, in order to corroborate the historic assays, especially as mineralisation is <50m, and to expand the known ore body.
CCZ said that at the Big One Deposit, the data was sourced directly from the previous holder and comprised a wealth information including field mapping campaign data sets, information memorandums, faxes, and reports with production summaries.
This includes ~4,400t of supergene ore mined from the Big One Deposit within the historic mining lease (ML5481), with an average achieved grade of ~3.5% Cu in 1997. In addition, historic production records for Boomerang Mine from 1944-74 verified that 4,211.2t of oxide ore was mined grading circa 6% Cu, with output of 250.9t copper metal.
Mt Oxide project
The Mt Oxide Project is located in the exciting Mt Isa region, northwest Queensland. The project includes two contiguous tenements. The tenure is within close proximity of the historic Mt Oxide Copper Mine which was re-commissioned in 2017.
Review of historic data
The company announced that the comprehensive review of historic data for the Big One Deposit and Boomerang Mine, within the Mt Oxide pillar in Mt Isa’s copper-belt was recently completed. CCZ said that they have been verified as highly prospective priority targets.
CCZ said that its geology team had to track down the previous holder of the Big One Deposit mining tenure to secure the historic information. This included various field mapping campaign data sets, information memorandums/reports, faxes and production summaries.
Excellent historic intercepts at Big One deposit
The company reported that in 1993, WME completed an RC drilling campaign at the Big One Deposit, comprising 27 drill-holes (aggregating 1,673m2). CCZ said that the assay results had excellent economic copper intercepts up to 28.4% Cu.
Significant hits include 3m @ 12.25% Cu from 42m incl: 2m @ 17.87% Cu from 43m; and 1m @ 28.40% Cu from 44m (B07); 8m @ 2.33% Cu from 44m incl: 6m @ 3.00% Cu from 45m; and 5m @ 3.28% Cu from 45m (B05); 4m @ 2.20% Cu from 44m incl: 2m @ 3.19% Cu from 46m and 1m @ 3.63% Cu from 47m (B06); 6m @ 1.55% Cu from 66m incl: 5m @ 1.79% Cu from 66m and 2m @ 2.08% Cu from 66m (B25); 3m @ 1.36% Cu from 73m incl: 2m @ 2.29% Cu from 73m and 1m @ 1.02% Cu from 74m (B26); and 2m @ 1.45% Cu from 36m incl: 1m @ 2.48% Cu from 37m (B02).
The company said that in 1997, ~4,400t of supergene ore was mined from the Big One Deposit within the historic mining lease (ML5481), with an average achieved grade of ~3.5% Cu.
CCZ said that for the Boomerang Mine, historic production data was reported in a Geological Survey of Queensland report.
The company reported that a review of legacy mineral production records at the Boomerang Mine stretched from 1944-74 verified that circa 4,211.2t of oxide ore had been mined grading a significant ~6% Cu, producing 250.9t copper metal.
Castillo reported that fieldwork is now imperative to determine the optimal next steps in developing a staged exploration campaign for investigating the Boomerang Mine.
Updates and further work
The company reported that bundling the Big One and Boomerang prospects with the large massive sulphide target at the Arya prospect delivers a significant pipeline of future development work.
CCZ said that its focus will be on putting in place a timeline to conduct a comprehensive site visit to the Big One Deposit, Boomerang Mine, and Arya Prospect as all three reinforce the importance of developing the top priority Mt Oxide pillar.
CCZ said that work is ongoing in reviewing the breadth of the information contained in the historical document package obtained from the last Holder of the ‘Big One’ mine (ML 5481) tenure. This includes follow up desktop investigations in regards to the ‘gossan’ mineralisation noted ‘to the north of the Big One Deposit’.
Castillo Copper’s Managing Director Simon Paull said: “Locating this historic drilling, assay and production data for the Big One Deposit and Boomerang Mine within the 961km2 Mt Oxide pillar, which is in the heart of the Mt Isa copper-belt is a tremendous windfall.
As a starting point, our geology team now have ample data points to start formulating a drilling campaign to re-test and potentially expand the known ore body at the Big One Deposit then focus on Boomerang Mine and Arya Prospect. This would be a great start to developing the high-priority Mt Oxide pillar and creating incremental value for shareholders.”
CCZ’s London based Director Ged Hall said: “The copper grades found at the Big One Deposit are excellent and clearly highlight the potential upside apparent from developing the Mt Oxide pillar.
More significantly, the timing is near text-book as we work towards securing regulatory approval to dual list CCZ on the Standard Board of the London Stock Exchange.”