Cygnus Metals’ 9.1 per cent copper hit at its Canadian Chibougamau copper-gold project leads the way on this week’s Bulls N’ Bears Big Hits list. Brazilian Critical Minerals has another interesting drilling underway at its Ema rare earths project in Brazil, as does Astral Resources at its Mandilla gold project near Kalgoorlie in Western Australia.
Let’s dive in.
Cygnus Metals
Chibougamau copper-gold project, Canada
Hit:7.3m at 4.2 per cent copper, 0.3g/t gold & 16.6g/t silver from 317.8m, including 2.5m at 9.1 per cent copper, 0.5g/t gold and 31.4g/t silver.
Cygnus Metals believes it has uncovered a new copper lode about 250 metres east of the footwall of its existing resource in the Corner Bay deposit in central Quebec, Canada, about 480 kilometres north of Montreal.
The discovery came from the first hole in the company’s program to target the footwall of the Corner Bay deposit, which jagged an intercept of 7.3 metres at 4.2 per cent copper, 0.3 grams per tonne (g/t) gold and 16.6g/t silver from 317.8m, including 2.5m at 9.1 per cent copper, 0.5g/t gold and 31.4g/t silver.
Corner Bay forms the primary deposit of Cygnus’ current Chibougamau copper-gold project. Corner Bay has an indicated resource of 2.7 million tonnes at 2.7 per cent copper and 0.3g/t gold and an inferred resource of 5.9mt at 3.4 per cent copper and 0.3g/t gold.
Cygnus says the Chibougamau district is a world-class mineral terrane with high potential for additional discovery, having historically produced more than 945,000t of copper and 3.5m ounces of gold.
Before the company’s merger with Doré Copper Mining, both companies had undertaken targeted exploration to test the immediate area around the Corner Bay deposit to identify new structures and extensions to the current resource.
The company sees the result as highlighting strong potential for multiple sub-parallel lodes at Corner Bay, which could be analogous to other well-known deposits in the region
A follow-up downhole electromagnetic (DHEM) survey of the hole identified a significant off-hole conductor measuring about 530m by 460m, which has yet to be drilled and sits south of and down-dip from the recent intercept.
Two additional conductors thrown up via a fixed loop electromagnetic survey lie about 100m to 300m south of the newly identified conductor and appear to lend further support to the possibility of main or repeat lode extension in that direction, about 400m to 800m below surface.
The southernmost conductor is also open to the south and to a greater depth, potentially as deep as 1000m below surface.
Cygnus Metals’ diamond drill core assayed 7.3m at 4.2 per cent copper, 0.3g/t gold and 16.6g/t silver from 317.8m, including 2.5m at 9.1 per cent copper, 0.5g/t gold and 31.4g/t silver. Image shows core between 321.9m and 322.6m. Credit: File
EM geophysics is known to correspond well with the mineralisation style at the Chibougamau mining project, which is primarily composed of chalcopyrite with minor amounts of pyrite and pyrrhotite.
Historically, airborne EM surveys were used to help make some of the discoveries in the region, however modern ground and DHEM surveys appear to have been under-used recently. The new electromagnetic anomaly offers a priority target for follow-up exploration along the Corner Bay structure.
The deposit extends 1350m below surface and is open to the north and to depth.
Its structurally controlled mineralisation is hosted as a north-south striking quartz-carbonate vein with semi-massive chalcopyrite and minor pyrite mineralisation. The main lode has been cross-cut and offset by a large dolerite dyke, with the upper and lower parts of the lode on either side of the dyke.
The Corner Bay deposit sits on the southern flank of the Chibougamau pluton and has seen minimal exploration compared to the northern flank.
Due to the relatively early stage of its definition, potential parallel lodes and resource extensions of the Corner Bay deposit have not been fully explored. The latest intercept highlights the potential for additional sub-parallel lodes within the immediate vicinity of the current resources.
The Chibougamau project is centred on the Chibougamau pluton, which has a district-wide historic production of 53.5mt at 1.8 per cent copper and 2.1g/t gold, with periodic mining undertaken from the early 1900s until 2008.
Throughout that time, the district produced more than 945,000t of copper and 3.5m ounces of gold from 16 former producing mines.
The project has high-grade resources including measured and indicated resources of 3.6m tonnes at 2.5 per cent copper and 0.6g/t gold, accompanied by inferred resources of 7.2mt at 3 per cent copper and 1.1g/t gold with significant growth potential.
Cygnus has two diamond rigs already on hand at Corner Bay and other nearby drilling targets.
The company has a clear strategy to expand its resources through brownfield exploration and by drilling to move the project towards development through studies and using existing infrastructure.
It sees a big opportunity to develop a sound project with an established high-grade resource with excellent infrastructure, a 900,000 tonnes per year processing plant and a clear pathway to production, all within an underexplored tier-one mineral district.
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Brazilian Critical Minerals
Ema ionic rare earths operation, Apuí region, Brazil
Hit: 10m at 1273ppm TREO from 7m, ending in 1183ppm TREO
Brazilian Critical Minerals third batch of infill auger drillholes at its Ema rare earths project in Brazil has confirmed widespread mineralisation across most of its planned central starter area.
The program is aimed at outlining a mineral resource estimate and produced a best result of 10 metres at 1273 parts per million (ppm) total rare earths oxides (TREO) from 7m, ending in 1183ppm TREO.
Two other high-value intercepts came in at 10m going 1214ppm TREO from 6m, ending in 824ppm TREO, and 8m at 1189ppm TREO from 11m, ending in 466ppm TREO.
The sample batch comprises 76 holes from the company’s mineral resource infill drilling last year and continues to show excellent grades and thicknesses in line with previous results. Mineralisation is confirmed as widespread within the central starter area over 21 square kilometres.
Results to date confirm the starter area alone should be able to support a long-life rare earth project, with all mineralisation lying 20m from the surface, which is ideal for in-situ recovery mining techniques.
The Ema ionic rare earths project is unique among Brazilian rare earths projects in that it shares almost identical characteristics with the ionic rare earths deposits developed across volcanic rocks in southwest China and Myanmar. These are the world´s largest known ionic clay regions and produced a significant proportion of the world’s rare earth elements output last year.
Exploration drilling at Ema is undertaken with hand-held auger drills, which offer the advantage of a low cost, rapid deployment and mobility – but have depth limitations. The deepest holes, generally containing the highest-grade results, sometimes need to be drilled to about 20m.
Most of the exploration so far has been conducted on widely spaced, 800m centres, with infill drilling on 300m centres in the central resource area.
Infill drilling at 300m centres offers a more detailed insight into the mineralisation grade and thickness and improves confidence in the mineral resource estimate.
The transition to closer auger spacing has led to the identification of some exceptional intercepts, suggesting the presence of high-grade pods within the mineralised zones.
The findings will be crucial for the next phase of exploration as the team works to define these high-grade areas for potential in-situ recovery.
For the first quarter of this year, the program at Ema will comprise finalising analyses of samples from the mineral resource infill drilling program, with all assays expected in the first quarter
Additionally, processing and metallurgical testing will involve complete magnesium sulphate leaching assays from each metre of every hole to extract additional data from selected infill drilling holes.
These results will underpin and support both the resource update and the scoping study and create a geo-metallurgical model to assist with the next phases of project design.
Comprehensive metallurgical tests will be undertaken on a representative master sample to determine processing characteristics from the current infill program, with work to be completed by the Australian Nuclear Science and Technology Organisation.
An updated resource estimate will seek to convert the entire infill drilling area to indicated status in March and April.
This will be followed by a scoping study which, with reference to the updated resource estimate, latest metallurgical test results and groundwater modelling data, is nearing completion and due for release during the current quarter.
Brazilian Critical Minerals major exploration focus is in the Apuí region in Brazil, where it has discovered a world class ionic adsorbed clay rare earth elements deposit. The Ema project is contained within a 781 square kilometre exploration tenement area in the Colider Group, where the company has defined an inferred mineral resource of 977mt of rare earths. Its metallurgical recoveries average about 68 per cent magnet rare earths oxides, recognised as being among the best for these types of deposits anywhere in the world.
The company is currently converting the mineral resource from inferred into the indicated category with an extensive drilling program to support the current scoping study and economic analysis scheduled for completion this quarter.
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Astral Resources
Mandilla gold project near Kalgoorlie, WA
Hit: 28m at 2.63g/t gold from 149m depth, including 0.5m at 115.7g/t gold from 152.3m and 0.3m at 20.3g/t gold from 173m.
Astral Resources has nailed good gold runs along much of a core from two diamond drill holes at its Theia deposit in the company’s 1.3m ounce Mandilla gold project near Western Australia’s Kalgoorlie mining centre. This included a best grade of 0.5m at 115.7g/t gold in the upper parts of the first hole.
The hole also produced a string of separate intercepts, with the best of 12.3m at 1.77g/t gold from 279.7m, including 0.4m at 37.9g/t gold from 289.6m and a further 56.7m at 0.64g/t gold from 403m, including 0.53m at 14.4g/t gold from 406.62m and 0.3m at 13.0g/t gold from 447.85m.
The intercepts are interspersed by multiple short lower grade hits typically ranging from 1m to 15m running at 0.31g/t to 0.72g/t gold.
When all the intercepts were combined, the hole delivered 172 gram-metres of gold mineralisation over the length of the hole.
The second hole ran to a depth of 452.6m and delivered an impressive string of eight separate intercepts. While typically these comprise longer runs of low to medium grade results in the 5m to 39m range at grades from 0.58g/t to 1.81g/t, each run included a high grade zone of 0.3m to 0.45m ranging between 13.7g/t and 59.9g/t gold.
When all these results were combined, the second hole returned 199 gram-metres of gold mineralisation over the length of the hole.
Astral’s Mandilla gold project sits in the northern Widgiemooltha greenstone belt, about 70km south of Kalgoorlie.
It comprises the Theia, Iris and Eos deposits spread over about 3400m within a north-west/south-east trending shear corridor. A fourth deposit, Hestia, is about 1km west of Theia on a separate parallel north-west trending structure.
The Theia deposit hosts an estimated mineral resource of 29mt at 1.1g/t gold for 1.02m ounces of contained gold, including the higher confidence indicated category of 17mt at 1.1g/t gold for 571,000t of contained gold. This makes up about 56 per cent of the total resource estimate.
Gold mineralisation at Theia and Iris is hosted within structurally controlled quartz vein arrays and hydrothermal alteration near the western margin of Emu Rocks granite and is in contact with sediments of the Spargoville Group.
Significant north-west to west-northwest-trending structures along the western flank of the project are interpreted from aeromagnetic data to cut through the granitic intrusion. These structures are considered important in localising gold mineralisation at Theia, which has a mineralised footprint extending over a strike length of more than 1.6km.
A second sub-parallel structure hosts gold mineralisation at the nearby Iris deposit to the south. The mineralised footprint at Iris extends over a strike length of about 600m and, when combined with Theia, forms a mineralised zone extending over a strike length of more than 2.2km.
The two diamond holes are part of a four-hole program completed in December aimed at converting deeper inferred resources at Theia to the higher indicated category.
They were designed to intersect mineralised quartz vein sets at Theia on a slightly oblique angle to test a bigger part of the deposit with each hole.
The company realised its expectation to bag multiple mineralised intercepts in each hole by using the orientation.
When aggregated, the mineralised sections returned 172 gram-metres and 199 gram-metres in the first and second holes respectively.
The company says the intercepts appear to conform well to the current mineral resource model and contribute to the expectation of higher confidence in its imminent resource model update slated for the March quarter.
Assay results for the final two diamond drill holes are expected to be received shortly.
Is your ASX-listed company doing something interesting? Contact: matt.birney@businessnews.com.au
By Doug Bright
