Core Energy (ASX:CR3) hits 12.3m at 2,015ppm TREO from surface at Tunas

Magnet rare earths run at 26% of the basket and the system is still open at depth

Auger drilling is the cheapest way to find out if a rare earths project is worth chasing, and Core Energy Minerals (ASX:CR3) just delivered the kind of infill results that tend to unlock the next stage of spend. The Tunas Project in southern Brazil has returned 12.3 metres at 2,014.9ppm total rare earth oxides (TREO) from surface in hole TNTR018, with an internal zone running 7.3 metres at 2,627.4ppm.

Hole TNTR017 went deeper into the saprolite and pulled 3.3 metres at 2,261.2ppm TREO from 7 metres down, with an interior intercept of 2.3 metres at 2,822.4ppm. These are grades that, for an ionic adsorption clay (IAC) style system, sit comfortably in the conversation with other listed Brazilian peers.

For investors, the more interesting number is the magnet rare earth ratio. The recent batch averaged 26% magnet rare earth oxides (MREO) as a share of TREO, peaking at 41%. That is the slice that matters because neodymium, praseodymium, dysprosium and terbium are what the electric motor and wind turbine supply chains actually pay for.

All holes ended in mineralisation. Fourteen further holes are still at the lab.

Why the magnet ratio changes the Tunas conversation

Plenty of rare earth projects can find big TREO numbers. Far fewer can find big TREO numbers where the magnet rare earths make up a quarter or more of the basket. That distinction is what separates a project that prices off lanthanum and cerium (cheap, oversupplied) from one that prices off NdPr and the heavies (constrained, strategically sensitive).

At Tunas, NdPr values inside the high-grade zone of TNTR018 hit over 1,000ppm in single metre intervals. For an early-stage auger program, those are eye-catching numbers and they are sitting from surface. The mineralisation also carries dysprosium and terbium signatures, which is what tips a basket from interesting to investable in current markets.

The leach test is the only data point that really counts next

We think the market is right to treat these grades as encouraging but not yet bankable. The whole IAC thesis hinges on whether the rare earths actually desorb cheaply at ambient temperature using mild acid or salt solutions. Without that, you have a clay deposit with high TREO and no economic flow sheet.

Management has now initiated leach testwork on the bulk residual samples, and the announcement flags a range of leach tests rather than a single optimised one. That is sensible at this stage, but it also means investors are still some quarters away from the metallurgical data that genuinely de-risks the project.

Our concern is that this is the moment where a lot of Brazilian IAC stories have historically wobbled. The grades look like Tier 1 IAC analogues. Recoveries don’t always follow.

Location, scale and what still has to be proven

Tunas sits 75km from Curitiba and 162km from the port of Paranaguá, which is genuinely useful infrastructure for a project that may eventually need to truck low-grade clay. The tenure covers 18.32 square kilometres across two granted exploration permits, both 100% owned through Core Energy’s Brazilian subsidiary.

Of the 19 holes in this campaign, only five have reported assays. The remaining 14 will land in coming weeks and will either tighten the geological model or expose gaps in it. With holes ending in mineralisation and no fresh basement encountered, the depth extent of the system is still genuinely unknown.

The Investors Takeaway for Core Energy Minerals

The next 90 days carry two binary catalysts for Core Energy. The remaining 14 auger assays will tell investors whether the high-grade zone in TNTR018 was a sweet spot or a system. The first leach results will tell them whether any of it can be extracted economically.

Investors can find more in-depth coverage of ASX-listed rare earths names at stocksdownunder. For now, Tunas has earned the right to a bigger drill program. Whether it earns the right to a resource estimate depends on what comes out of the leach beaker, not the auger flight.