Cooper Metals Ltd reports Mt Isa East Project assay results
Published by Jessica Casey,
Global Mining Review,
Cooper Metals Ltd (CPM) has reported the continuation of encouraging assay results from follow up reconnaissance rock chip geochemical sampling during a recent field trip to the Mt Isa East Project in northwest Queensland.
- Infill rock chip sampling along the 1.5 km copper (Cu) mineralised trend at King Solomon returns up to 9.85% Cu and 2.58 g/t gold (Au), indicating higher Au potential than previously envisaged.
- Further old workings found at Python prospect, extends known mineralisation, with 8.53% Cu and 0.11 g/t Au returned from rock chip sample near historical mine shaft.
- Yarraman historical Cu in soil anomaly extends for 400 m centred on old workings, with Cooper rock chip samples up to 3.31% Cu returned from historical shaft.
- Rock chip samples up to 20.2% Cu from gossanous outcrop 640 m southeast of Yarraman workings indicates broader potential of the area.
- High powered ground EM at Python progressing.
Cooper Metals Managing Director, Ian Warland, commented: “Follow-up surface geochemical sampling in the north-eastern part of the Mt Isa East Project continues to impress and build an exciting picture of the broader Cu-Au potential of the project area. The highest gold result to date of 2.58 g/t Au at King Solomon highlights the strong gold potential of the prospect, which was mainly exploited by historical miners for the copper mineralisation. At Python, the footprint of the old workings and Cu mineralisation continues to grow as field teams continue to explore the area. The high-powered electromagnetic survey underway at Python is designed to aid interpretation of the mineralisation in three dimensions and delineate preliminary drill targets.”
“Initial field reconnaissance at other prospects has been very encouraging including Yarraman area, which returned up to 20.2% Cu from an iron oxide gossan hosted in a significant shear zone within mafic rocks, which are often spatially associated with Cu-Au mineralisation in the region. I’m very pleased with the company’s progress at assessing Cu-Au occurrences and targets to date, the company is planning to move into less explored areas of the prospective Mary Kathleen Domain with airborne electromagnetic survey to start after the wet season.”
Cooper has recently commenced exploring for Cu-Au mineralisation at the Mt Isa East Project. The project area covers part of the Mary Kathleen Domain within the world class Mt Isa Inlier that also hosts Carnaby Resources (Nil Desperandum and Lady Fanny prospects located just 10 km southeast of Cooper’s tenure.
After the success of Cooper's initial reconnaissance geochemical programme announced late last year, where samples up to 35.3% Cu were returned from Python prospect, results from follow-up sampling at several prospects including Python, King Solomon, Yarraman and Prince Albert Trend have been received.
An additional 18 rock chip samples were collected from historical workings and/or selected outcrops which contained visual evidence of copper mineralisation or appeared gossanous in nature. The reconnaissance field trip focused on the northeast portion of the project. The results extend mineralisation at Python and King Solomon and re-affirm Cooper’s positive view of the area, highlighting the prospectivity of the Mt Isa East Project for Cu-Au deposit potential. A summary of key results appears below:
King Solomon Cu-Au Prospect
At the King Solomon Prospect, several old (artisanal) copper workings strike over a length of 1.5 km within the lower Corella Formation close to the contact with the underlying Ballara Quartzite. Past production from the King Solomon Group is quoted as producing 894 t at 5.3% Cu with a further 2195 t of cupriferous limestone flux at 2.3% Cu. Historical mining focused on copper oxide and native copper from three main locations along strike, King Solomon 1, 2 and 3. The initial reconnaissance sampling at King Solomon by Cooper collected rock chip samples focusing along the King Solomon line of workings, returning Cu assays ranging from 0.71% to 16.65% Cu.
Multiple mineralised lodes?
A new phase of sampling, reported here, was designed to infill along the King Solomon trend increasing the rock chip sampling from 13 – 20 samples. Encouragingly, assay results up to 9.85% Cu and 2.58 g/t Au (MER058) were received, with the Au grade significantly higher than any previously reported at King Solomon. Cooper’s mapping and sampling indicates an offset of the mineralisation to the east by approximately 50 m in the central area between King Solomon 1 and 2. Importantly, there are no historical workings here and the offset mineralisation may represent a parallel load, with the main load position to the west obscured by cover. Further mapping and subsequent drilling is required to resolve the geological structure and potential opportunity to extend the mineralisation.
The current sampling results supports minimal historical rock chip sampling at the King Solomon prospect completed in 2014 by Chinalco, that also returned significant Cu and Au values, with the best results; 1.74 g/t Au from rock chip sample 411839 and 20.9% Cu from 411843 (King Solomon 3).
Significantly, the Qld governments GeoResGlobe database does not record any historical drilling at King Solomon prospect, nor was there any evidence on the ground for historical drill collars.
The Python prospect is located approximately 2.3 km to the northwest of the King Solomon prospect and consists of a series of small shallow workings and a single shaft within limestone of the Corella Formation. Cooper previously collected three rock chip samples from the shallow workings at Python that returned copper grades from 1.65% to 35.3% Cu. During the current sampling campaign, an additional previously unknown historical mining shaft, south along strike from the shallow pit workings was located. Assay results from a grab sample near the shaft returned 8.53% Cu and 0.11 g/t Au (MER048). Sample MER046 returned 8.12% Cu and 0.82 g/t Au from a shallow pit just to the north. Historical exploration by Syndicated Metals collected two rock chip samples from the Python prospect in 2008 with sample 9848 returning 1.23 g/t Au and 12.1% Cu.
Mineralisation has been found extending over 250 m of strike at Python and appears to be associated with a north–northeast trending fault. Based on the extent of mineralisation observed and degree/strength of Cu and Au anomalism Cooper commenced a ground electromagnetic survey at Python in late January 20224.
The Yarraman prospect is located approximately 14 km southwest of King Solomon prospect. Reconnaissance geological mapping by Chinalco between 2010 and 2013 delineated a zone of shear-hosted Cu mineralisation along the structural contact between the Kalkadoon Granite and an amphibolite/dolerite unit, and possibly the structural confluence with the Leichhardt Volcanics which comprise a sequence tuffaceous rhyolite, dacites and quartzites. The lithological setting is considered highly favourable because mafic intrusives (which occur throughout the Mount Isa Inlier (such as metadolerites, amphibolites, mafic dykes, diorites and minor gabbro) commonly have a spatial association with Cu-Au deposits.
Historical soil sampling programmes at the Yarraman prospect defined a clear mineralised trend (northeast) outlined by a Cu-in-soil anomaly over a strike length of ~approximately 400 m. Two historical shafts are located near the centre of the soil anomaly. The Yarraman mineralisation has never been followed up with surface geochemistry to confirm the Cu mineralisation associated with the soil anomaly or historical workings and has not been tested with exploration drilling.
Cooper geologists visited Yarraman prospect in late 2021 to verify the previous exploration work collecting five rock chip samples from the wider area including two in the vicinity of the historical workings. MER057 grab sample returned 3.31% Cu adjacent to the shaft and rock chip sample MER056 returned 1.92% Cu approximately 90 m to the southwest.
Significantly, Cu mineralisation up to 20.2% with anomalous Au 0.18 g/t Au and silver 3.9 g/t Ag (MER054) was found in a rock chip sample from a gossanous sheared mafic schist 640 m to the southeast of Yarraman workings indicating Cu potential in the area is much broader and may be associated with north easterly trending shear zones in proximity to mafic rocks.
Current and planned work at Mt Isa East Project includes:
- Ground electromagnetic survey at King Solomon and Python Prospects to delineate any sulfide conductors for drill testing.
- Continued compilation and integration of historical exploration results from the project area.
- Extensive follow-up mapping and geochemical programs at lesser developed targets (Prince Albert, Yarraman, Mt Zsu Sui), to start to build a more accurate picture of the extent of some of these strongly mineralised systems.
- A regional airborne electromagnetic survey in early June quarter.
Read the article online at: https://www.globalminingreview.com/exploration-development/07022022/cooper-metals-ltd-reports-mt-isa-east-project-assay-results/
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