Magnum’s rare earth assays sharpen the Plateau resource case

The most important result from Magnum Mining and Exploration Limited (ASX:MGU; OTCID: MGUFF) is not the highest total rare earth grade. It is the growing evidence that Piracanjuba North’s economic story, if one emerges, will depend on what the clay releases in testing rather than what the rock contains in total.

Assays from another 65 auger holes have taken the reported dataset to 373 of 894 drilled holes, with 521 still pending. Within the priority Plateau Zone, 200 paired holes covering 1,385 metres of sampling produce a length-weighted average of 160 ppm desorbable total rare earth oxide, or D-TREO. The company says magnet rare earth oxides account for 33.1% of D-TREO, compared with 23.7% of head-grade TREO.

Desorbable grade separates the stronger targets

The contrast between total grade and desorbable response is stark. PIR-AH-0315 recorded the batch’s highest head grade at 1,904 ppm TREO, but released only 16 ppm D-TREO, or 0.9%. PIR-AH-0339, by comparison, contained 385 ppm TREO and released 176 ppm D-TREO, equivalent to 46%.

That distinction is driving Magnum’s targeting. PIR-AH-0339 returned 15 metres at 176 ppm D-TREO from surface, including 2 metres at 471 ppm from 10 metres. PIR-AH-0346, outside the Plateau, returned 12 metres at 203 ppm D-TREO from surface, including 2 metres at 506 ppm from 2 metres. Across the new batch, whole-hole D-TREO ranged from 0.85 ppm to 202.59 ppm, while the strongest individual interval was 2 metres at 515.41 ppm in PIR-AH-0333.

Plateau data now supports resource prioritisation

The Plateau’s average is higher than the 127 ppm D-TREO recorded across all 338 qualifying holes reported to date. The data also shows a recurring shift towards magnet elements in the desorbable fraction, with the magnet share higher in 194 of 200 qualifying Plateau holes. Magnum attributes that pattern to the behaviour expected in ionic adsorption clay deposits, where cerium largely remains attached to the clay while other rare earths are more readily released.

There is still a substantial geological qualification. These are laboratory screening results produced under an ammonium sulphate protocol at initial pH 4, not process recoveries, product yields or economic recoveries. The reported intervals are apparent down-hole lengths from vertical auger holes, and true widths and lateral continuity remain unestablished. The company also notes that the screening conditions have not been optimised.

Diamond drilling will support confidence and metallurgy

Magnum says the samples intended for the initial resource estimate are already at the laboratory, meaning the planned 2,000-metre diamond programme is not intended to add holes to the maiden MRE dataset. Instead, the water-free drilling is designed to improve geological control, collect density measurements, obtain representative mineralogical and metallurgical samples, and test the continuity of higher-response saprolite at depth and along strike.

The immediate sequence is therefore assay completion, certificate reconciliation, database freeze, geological domaining and QAQC sign-off, alongside mineralogy, clay characterisation, metallurgical testing and NORM assessment of process solutions, products and residues. Magnum is targeting the maiden JORC MRE for the end of November 2026, subject to assay timing and the technical work still to be completed.