Mosaic Begins a Drilling Campaign of at Least 2,000 Metres at Golden Island and Returns up to 72.8 g/t Au, 42.5 g/t Ag and 0.42% Cu at Surface
Montreal, Quebec–(Newsfile Corp. – October 29, 2026) – Mosaic Minerals Corporation (CSE: MOC) (“Mosaic” or the “Company”) announces assay results for 343 samples collected during its summer 2026 exploration campaign on its Golden Island gold project in Abitibi, Quebec. The Company also announces the start of its diamond drilling campaign of at least 2,000 metres on the project. The drill rig and drilling crew are now on the island.
Highlights
- Gold grades: 72.79 g/t Au (C0381259) and 66.92 g/t Au (C0380541).
- Polymetallic mineralization: Sample C0381259 also returned 42.5 g/t Ag and 0.42% Cu.
- Coarse gold confirmed (nugget effect): Following receipt of the initial results, which showed high variability, Mosaic ordered metallic screen re-assays on the high-grade samples. This method confirmed the presence of coarse gold, with fractions grading up to 2,842 g/t Au.
- Sampling results: Of the 343 samples, 9 assayed above 10 g/t Au, 17 above 5 g/t Au, and 45 samples (13% of the total) exceeded 1 g/t Au.
“These results confirm the presence of high-grade gold across a large part of the areas sampled at Golden Island,” said Jonathan Hamel, President and CEO of Mosaic. “With nine samples above 10 g/t Au and the recurring presence of coarse gold, we are now moving to drilling. The rig is in place on the island, and our campaign of at least 2,000 metres will test the high-grade zones identified at surface at depth.”
Start of the 2,000-Metre Drilling Program
The surface results detailed above, combined with geophysical surveys (Mag-VLF), allowed the technical team to refine the drill targets. The drill rig and heavy equipment were transported to Golden Island by barge. The diamond drilling program, comprising a minimum of 2,000 metres in about a dozen holes, is officially under way. The primary objective is to test the down-dip geometric extension of the high-grade vein systems identified in the trenches, to depths ranging from 150 to 300 metres.
Best Gold Results (≥ 5 g/t Au)
| Sample | Au (g/t) | Method Used | Other Au Assays (g/t) | Ag (g/t) | Cu (ppm) |
| C0381259 | 72.79 | Gravimetric | 116.26 (dup.) | 42.5 | 4,220 |
| C0380541 | 66.92 | Metallic screen | 154.70; 619.17 (grav.) | 2.8 | 12 |
| C0381370 | 54.51 | Gravimetric | 55.30 (dup.) | 0.8 | 16 |
| C0381442 | 38.81 | Gravimetric | 44.95 (dup.) | 1.8 | 17 |
| C0381449 | 33.36 | Gravimetric | 32.43 (dup.) | 3.5 | 15 |
| C0381440 | 18.96 | Gravimetric | 3.77 (dup.) | 0.4 | 27 |
| C0380511 | 18.35 | Metallic screen | 33.26 (grav.) | 0.2 | 16 |
| C0381451 | 16.97 | Gravimetric | – | 0.4 | 23 |
| C0381448 | 12.03 | Gravimetric | 9.74 (dup.) | 5.4 | 17 |
| C0381271 | 9.46 | Gravimetric | 12.65 (dup.) | 1.3 | 174 |
| C0380502 | 9.35 | Metallic screen | 7.44 (grav.) | 0.7 | 42 |
| C0381450 | 8.81 | Gravimetric | – | 0.4 | 23 |
| C0381270 | 7.89 | Gravimetric | – | 0.5 | 84 |
| C0381252 | 7.75 | Gravimetric | 5.38 (dup.) | 8.9 | 147 |
| C0381269 | 6.86 | Gravimetric | 3.74 (dup.) | 1.7 | 64 |
| C0381444 | 6.20 | Gravimetric | – | 1.0 | 21 |
| C0381283 | 5.79 | Gravimetric | 18.93 (dup.) | 0.4 | 77 |
The grade reported is the metallic screen result where one was performed; otherwise, it is the original gravimetric assay. Laboratory duplicates are shown for information only and are not averaged.
Best Silver Results (≥ 2 g/t Ag)
| Sample | Ag (g/t) | Au (g/t) | Cu (ppm) |
| C0381259 | 42.5 | 72.79 | 4,220 |
| C0381265 | 10.0 | 1.68 | 212 |
| C0381252 | 8.9 | 7.75 | 147 |
| C0380592 | 6.0 | 0.01 | 40 |
| C0381448 | 5.4 | 12.03 | 17 |
| C0381284 | 5.4 | 0.10 | 55 |
| C0381449 | 3.5 | 33.36 | 15 |
| C0381386 | 3.1 | 2.40 | 35 |
| C0380541 | 2.8 | 66.92 | 12 |
| C0381300 | 2.1 | 0.03 | 204 |
Best Copper Results (≥ 150 ppm Cu)
| Sample | Cu (%) | Cu (ppm) | Au (g/t) | Ag (g/t) |
| C0381259 | 0.42 | 4,220 | 72.79 | 42.5 |
| C0381318 | 0.17 | 1,740 | 0.04 | 0.9 |
| C0381324 | 0.05 | 532 | 0.08 | 1.8 |
| C0381265 | 0.02 | 212 | 1.68 | 10.0 |
| C0381274 | 0.02 | 208 | 2.43 | 0.6 |
| C0381300 | 0.02 | 204 | 0.03 | 2.1 |
| C0381273 | 0.02 | 176 | 0.31 | 0.8 |
| C0381271 | 0.02 | 174 | 9.46 | 1.3 |
| C0381289 | 0.02 | 163 | 0.05 | 0.6 |
| C0381291 | 0.02 | 152 | 0.02 | 0.2 |
Stripping and Channel Sampling Campaign
The 343 samples analyzed come from a mechanical stripping and historical trench cleaning campaign aimed at exposing bedrock. The samples, cut with a diamond rock saw, consist mainly of continuous channels averaging 0.5 metre in length.
Detailed mapping of the stripped areas confirms that the mineralization is hosted in a (blue quartz-eye) granodiorite. The gold system consists of a complex structural network of shear veins, sub-vertical tension veins and stockwork zones, often accompanied by pyrite, hematization and, locally, visible gold (VG).
Analytical Methods and Quality Control (QA/QC)
Samples were shipped to Laboratoire Expert Inc. in Rouyn-Noranda. Gold was first determined by fire assay with an atomic absorption finish (FA-GEO), and samples exceeding the upper detection limit were re-assayed by fire assay with a gravimetric finish (FA-GRAV). Silver and copper were determined by atomic absorption following aqua regia digestion (AAT-7).
Due to the presence of coarse gold (nugget effect) observed in the field and the high variability noted in the initial laboratory duplicates (e.g., sample C0380541 went from 154.70 g/t to 619.17 g/t in the gravimetric duplicate), Mosaic requested additional metallic screen assays (FA-MET) on the complete pulverized samples. This method, the most representative in the presence of coarse gold, confirmed high grades in the coarse fraction (+100 mesh), up to 2,842 g/t Au (C0380541).
Mosaic applied a quality control protocol by inserting certified reference materials (standards) and blanks at a rate of approximately one control per 20 samples.
No contamination was detected.
Qualified Person
The scientific and technical content of this news release has been reviewed and approved by Suzie Tremblay, Géo/P.Geo, a qualified person as defined by National Instrument 43-101 Standards of Disclosure for Mineral Projects. OGQ #10664
About Mosaic Minerals Corporation
Mosaic Minerals Corp. is a Canadian mining exploration company listed on the Canadian Securities Exchange (CSE: MOC). The Company is developing the Golden Island (Au), Amanda (Au) and Gaboury (Ni) projects located in Abitibi and James Bay (Quebec).
Source:
Jonathan Hamel
President and CEO
[email protected]
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