Key Highlights

  • A 14-metre channel returned 93.7% calcium fluoride at the historic Big Jim workings.
  • The channel includes 12 metres at 95.9%.
  • No vein sample returned less than 80%.
  • The Quinn fluorspar project is in Nevada, United States.

OD6 Metals (ASX:OD6) has reported the first systematic channel sampling at the historic Big Jim workings, part of its Quinn fluorspar project in Nevada, United States. The channel returned 14 metres at 93.7% calcium fluoride, the mineral that makes up fluorspar, including 12 metres at 95.9%. No vein sample returned less than 80%.

Managing director Brett Hazelden said channel sampling provided a meaningful step up in confidence from rock chips and substantially de-risked Big Jim as a near-term drill target.

Why the method matters

Channel sampling involves cutting a continuous line across exposed rock and collecting material in consecutive samples of fixed length, here two metres. Because each sample covers a defined interval, the results are more representative than selected rock chips, which can be biased towards the best-looking material.

The channel comprised eight contiguous samples running from the southernmost exposure, over the historic adit and along a cliff face to the north. The first six were massive fluorspar grading between 93.5% and 97.6%. The seventh, which included wall rock, returned 80.6%, and the eighth, entirely wall rock, returned 0.6%. OD6 says the sharp drop is consistent with a well-defined vein margin.

All samples were assayed by ALS Global.

Length, not thickness

An important point is orientation. The channel runs along the structure, so it measures the vein's length rather than its thickness. Big Jim is a shallow, west-dipping vein of near-pure fluorspar about two metres thick, sitting beneath a silicified breccia interpreted as the Saw Mill Thrust. The northern end of the channel marks the limit of accessible exposure, not the end of the vein, which continues under scree, covered workings and overlying rock.

History repeats

Hazelden said the results almost exactly replicated those reported from Big Jim in 1947, when channel samples of 90% to 94% and mine samples up to 98.6% were recorded over workings mapped for more than 220 metres. The new grades are also consistent with the 98.3% head grade of OD6's Big Jim metallurgical sample.

A narrow but very pure source

OD6 acknowledges that the veins are narrow compared with the 60-metre-wide replacement zone at Horseshoe and the 100-metre-wide breccia and stockwork zone at Mammoth. It argues, however, that their purity could provide compact, very high-grade sources of feed in a hub-and-spoke development.

Big Jim forms part of a corridor of about 700 metres with the Rocket and Spar structures, containing at least four mineralised structures. A new rock chip from upper Rocket returned 99.9%, and Spar has returned up to 94.3%.

The commercial angle

The company says near-pure fluorspar with low impurities and strong ore-sorting performance could support a lower-capital route to a direct-shipping metallurgical-grade product, known as metspar, before any flotation circuit for premium acid-grade fluorspar above 97%. It notes that the United States imports all the fluorspar it consumes, which underpins interest from policymakers.

Those are potential pathways, not plans with approved economics. No resource has been estimated at Quinn, and the tonnage in narrow veins may be limited.

What fluorspar is used for

Fluorspar is the main source of fluorine for the chemical industry, used to make hydrofluoric acid, refrigerants, fluoropolymers and Lithium-Ion Battery electrolytes. Metallurgical-grade fluorspar is used as a flux in steelmaking. Both the United States and the European Union classify it as a critical mineral.

Next steps

Quinn comprises 226 Mining claims over about 1,890 hectares, with more than 20 fluorspar occurrences along an eight-kilometre corridor. A plan of operations has been submitted and baseline surveys completed. Drill permitting through the US Forest Service is well advanced, and Big Jim is a clear priority target for maiden drilling, which will show how far and how deep the vein persists. Further mapping and channel sampling of Rocket and Spar will follow as access allows.