OD6 Metals (ASX:OD6) reports materially higher fluorspar grades from re-assayed channel samples at its Horseshoe prospect in Nevada, US.
According to the company, ALS Global laboratories had advised that the original assay technique used for Horseshoe channel samples can exhibit a negative bias for ‘high-grade’ fluorspar matrix, resulting in the underestimation of fluorine and calculated calcium fluoride grades.
Re-assays using an updated ALS method show an average increase of 12.9% in calcium fluoride (CaF2) compared with results originally reported on 8 July 2026.
Standout results from the expanded in-pit channel sampling include 50m @ 79.3% CaF2 in the southeast wall, previously reported as 63.9% CaF2, and 27m @ 65.1% CaF2 in the north pit, previously reported as 54.4% CaF2.
Meanwhile, the northwest wall combined returned 22m @ 78.8% CaF2, previously reported as 70.7% CaF2, including 9m @ 84.5% CaF2, previously reported as 74.4% CaF2. Central bench sampling delivered 15m @ 85.8% CaF2, previously reported as 65.8% CaF2.
The company reports 31 samples at Horseshoe returned grades exceeding 90% CaF2 with a peak value of 98.8% CaF2. All 120 channel samples averaged 74.8% CaF2, with 85% grading above 50% CaF2 and averaging 90.4% CaF2.
Managing Director Brett Hazelden says establishing the appropriate assay technique for ‘ultra-high-grade’ fluorspar mineralisation has been ‘essential’.
“ALS advised that the original method can underestimate fluorine for this specific high-grade matrix, and the re-assays now confirm that the previously reported Horseshoe grades were materially under-called,” Hazelden says.
“Grades approaching 80% CaF2, over significant widths, are exceptional in a global fluorspar context, particularly when they occur from surface within a broad replacement-style mineralised system.”
The company originally used the F-ELE82 technique for fluorine analysis, as the preferred F-XRF24 technique was not available locally.
OD6 now intends to use F-XRF24 for all future samples and says the new assay results align with recent large-format metallurgical samples that returned 90% CaF2 and 76.2% CaF2, as previously reported.
Hazelden notes Horseshoe is not presenting as a conventional narrow-vein fluorspar deposit. Rather, mineralisation is exposed across an approximately 80m-wide zone and previous drilling indicates a tabular body 15–30m thick.
The company reports mineralisation remains open up-dip beneath the silicified cap and down-dip beneath talus cover, signifying expansion potential.
“For investors, the significance is the combination of grade, width, and scale,” Hazelden says.
“These latest results, together with the exceptional grades being returned from our metallurgical samples, continue to strengthen our view that Horseshoe has the potential to become a significant high-grade fluorspar deposit.”
Acidspar prices in the US reached approximately US$654 ($914) per tonne in July, highlighting the potential value of producing ‘premium-grade’ fluorspar into a strategically important and import-dependent US market.
The Quinn Fluorspar Project covers 226 mining claims across approximately 1,890 hectares in Nevada and contains more than 20 fluorspar occurrences. The company says the US remains 100% reliant on imported fluorspar, with the mineral established on the US Critical Minerals list.
OD6 says it is now evaluating an initial staged development approach targeting early metspar (metallurgical-grade fluorspar) opportunities, followed by beneficiation studies to assess the production of ‘high-value’ acidspar products.
The company is currently advancing permitting programs including environmental baseline and archaeological studies, while progressing metallurgical test work with optical sorting and beneficiation studies to optimise premium product recoveries.
It is also preparing drilling and bulk sample approvals to demonstrate the scale of the Quinn system.
OD6 Metals is a critical minerals explorer and developer with projects spanning fluorspar, rare earth elements, and copper across the US and Australia.
Write to Paula Fabe at Mining.com.au
Images: OD6 Metals
