The Iron Creek Cobalt Project is located in Lemhi County, Idaho, USA, along the most prolific trend of cobalt mineralization in the USA, the Idaho Cobalt Belt (Figure 1). The property consists of mining patents and exploration claims covering an area of 1,698 acres. Significant infrastructure is in place to support multiple drills and underground activity. Historic underground development includes 600 metres of drifting from three adits and an all-weather road connecting the project to a state highway.
2018 Mineral Resource Estimate
In October 2018, First Cobalt filed its first NI 43-101 Mineral Resource Estimate for the Iron Creek Cobalt Project.
- Inferred mineral resources of 29.6 million tons (26.9 million tonnes) grading 0.11% cobalt equivalent (0.08% cobalt and 0.30% copper) under a base case scenario pit constrained and deeper mineral resource. An alternative underground-only scenario results in 4.9 million tons (4.4 million tonnes) grading 0.30% cobalt equivalent (0.23% cobalt and 0.68% copper)
- Resource contains 45 million pounds (20,411 tonnes) of cobalt and 175 million pounds (79,379 tonnes) of copper for 62.9 million pounds (28,528 tonnes) of cobalt equivalent
- Resource is considered to be open along strike and at depth, with true widths between 10m and 30m
- Preliminary metallurgical testing concludes that simple flotation methods are applicable, yielding recoveries of 96% for cobalt and 95% for copper in rougher floatation
The estimate of Inferred cobalt and copper resource is 29.6 million tons (26.9 million tonnes) at average grades of 0.08% cobalt and 0.30% copper, for a cobalt equivalent grade of 0.11%. These are reported at a cutoff of 0.03% CoEq for pit-constrained mineralization and 0.18% CoEq cutoff for potentially underground mineralization (Figure 2). As an alternative, an underground only scenario was estimated at a cutoff of 0.18% CoEq (Figure 3).
The tabulations at 0.15%CoEq, 0.20%CoEq and 0.35%CoEq represent material that could be available if only an underground scenario is to be considered.
- Mineral Resources which are not Mineral Reserves do not have demonstrated economic viability. The Inferred Mineral Resource in this estimate has a lower level of confidence than that applied to an Indicated Mineral Resource and must not be converted to a Mineral Reserve. It is reasonably expected that the majority of the Inferred Mineral Resource could be upgraded to an Indicated Mineral Resource with continued exploration. The Mineral Resources in this press release were estimated using the Canadian Institute of Mining, Metallurgy and Petroleum (CIM), CIM Standards on Mineral Resources and Reserves, Definitions and Guidelines prepared by the CIM Standing Committee on Reserve Definitions and adopted by CIM Council.
- Cobalt equivalent is calculated as %CoEq = %Co + (%Cu/10) based on US$30/lb Co and US$3/lb Cu. No metallurgical recoveries were applied to either metal because it is expected that the metallurgical recoveries will be similar for both metals.
- All classified resource blocks located between the surface and the open pit shell with grades greater than 0.03% CoEq were included in the reported mineral resources and resource blocks located below the pit-confining surface and with grades greater than 0.18% CoEq were included in the reported underground mineral resources.
- For the underground-only scenario, a 0.18% CoEq cutoff grade was used for estimating the potential underground material in the reported mineral resources
- The cutoff grade utilized in the above table was derived from US$30/lb Co and US$3/lb Cu.
Preliminary flotation tests were completed using three bulk samples extracted from one of three adits on the property. McClelland notes two samples had copper grades close to 1.0% and all three had cobalt grades in the range of 0.25% to 0.40%. All samples responded very well when subjected to rougher flotation using standard conditions. Copper recovery into the bulk concentrate averaged over 97% for the two high-grade samples and 92.5% for the low grade sample. Cobalt was recovered in the pyrite product. For all three bulk samples this product contained more than 90% of the cobalt at grades of 1.2% to 1.8% cobalt.
Iron Creek Property
The No Name and Waite Zones are roughly parallel and dip roughly 75° to the north, remaining open at depth. Additional mineralization has been encountered during drilling and some holes in the 2018 program are intended to confirm the potential for additional mineralized zones beyond No Name and Waite. The No Name Zone and the Waite Zone have true widths between 10m and 30m. Mineralization also occurs between the No Name and Waite Zones as 1m to 5m pods.
Cobalt-copper mineralization occurs as semi-massive and disseminated pyrite and chalcopyrite along stratabound bands within finely layered meta-sedimentary rocks consisting of interbedded argillite and quartzite. Cobalt is associated with pyrite. Thin veins of chalcopyrite also cut the bands and meta-sedimentary rocks. Quartzite units make up the hangingwall and footwall to the mineralized meta-sedimentary horizon. This stratigraphic sequence has been mapped at surface and by drilling to extend along strike for at least two kilometres.
The principal mineral assemblage consists of pyrite, chalcopyrite, pyrrhotite, and magnetite with much lesser quantities of native copper and arsenopyrite locally. Scanning-electron and microprobe tests indicate the cobalt occurs largely or entirely within pyrite and there is a distinct lack of cobaltite, a common cobalt ore mineral containing arsenic. Drill results demonstrate that the cobalt and copper mineralization are in part separated from each other spatially, and in part overlapping.