The next phase of drilling at Equinox Resources’ (ASX:EQN) Rio Negro target will aim to further delineate and map out the “ultra-high-grade” monazite-rich zones within the mineralised sill.
Equinox says that given the structural controls and observed continuity of rare earth mineralisation, the plan will focus on angled drilling to intersect the sill at optimal depths and orientations.
This approach is poised to help refine the geometry, thickness, and grade distribution of the sill-hosted rare earth mineralisation. The primary objectives will be to target ‘ultra-high-grade’ zones, such as the 7,890ppm TREO interval in hole CG_RC24_005 and identify similar zones laterally and at depth.
Additionally, the drilling will aim to map the geometry and continuity of the sill to confirm its dip, strike, and thickness variations, while assessing grade variability
Reporting on reverse circulation drilling assay results from the Rio Negro prospect within the Campo Grande Rare Earth Project in Bahia, Brazil, the company notes to date 2457.95m has been drilled, comprising 92 auger and 17 reverse circulation drillholes.
Bauxite with gallium oxide content has also been identified in the southeast corner of Rio Negro. The gallium (Ga₂O₃) and aluminium oxide (Al₂O₃) intercepts present a compelling case for mineralisation, the company adds.
This area is distinct from the central east part of the prospect, which hosts “high-grade” rare earth element mineralisation. Together, these zones demonstrate the diverse and high-value potential of the Rio Negro prospect, positioning it as a region of strategic importance for critical and industrial minerals.
In H1 2025, Equinox intends to test both the prospect’s reactive silica (SiO₂) levels and remaining Al₂O₃ assays. While the available data still indicate strong potential for high alumina recovery, the company says reactive silica content remains unknown.
Elevated reactive silica could increase caustic soda consumption and waste generation, potentially offsetting the benefits of high Al₂O₃ and Ga₂O₃ grades. Even if silica is found to be elevated, Brazilian bauxite is often beneficiated to reduce impurities prior to refining, underscoring the importance of these tests for fully assessing the mineralisation’s economic viability and refining strategies.
According to Equinox, the Rio Negro intercepts and Campo Grande Project present a multi-commodity opportunity, with gallium and aluminium oxide grades capable of meeting global demand in critical and industrial applications. The data indicates the project’s prospectivity to host world-class bauxite mineralisation with gallium as a high-value byproduct.
Equinox Resources Managing Director Zac Komur says the Rio Negro prospect is proving to be an exciting and important part of our Campo Grande Rare Earth Project.
“The standout TREO grades, including 7,890 ppm supported by monazite as the primary REE-hosting mineral, showcase the unique geological opportunity here. What’s just as exciting is the high-grade gallium and bauxite we’ve intersected in the southeast, with gallium grades exceeding global averages, a significant win for the project,” Komur says.
“And let’s not forget, Rio Negro represents only 1% of our broader 1,800 km² landholding at Campo Grande. There is untapped potential yet to be uncovered. We’re looking forward to seeing the upcoming results from the central and northern blocks. There’s a lot of work ahead, but with these results, we’re confident we’re on the right track to fully unlock the value of this project.”
Write to Adam Orlando at Mining.com.au
Images: Equinox
