Junior explorer Tribute Minerals (TBM-V) has tabled a resource estimate for the Arrow massive sulphide zone at its flagship Garnet Lake property in northwestern Ontario.
The estimate, by consulting firm Broad Oak Associates, puts the size of the Arrow zone at 1.3 million tonnes of indicated resources, at average grades of 8.12% zinc, 0.81% copper, 0.6 gram gold and 23 grams silver per tonne. Another 574,000 tonnes are inferred, with an average 4.34% zinc, 0.87% copper, 0.8 gram gold and 22 grams silver per tonne.
The estimate used a cutoff grade of 5% zinc-equivalent, based on zinc and copper content only. Copper was weighted at 2.4 times the value of zinc to calculate the cutoff. Moving that cutoff grade to 10% zinc-equivalent brought the tonnage down to 507,000 tonnes, all indicated, with average grades of 16.3% zinc, 1.25% copper, 0.8 gram gold and 29 grams silver per tonne.
The resource has a minimum width of 3 metres.
Recent laboratory work has shown trace values of indium and gallium in the mineralization; both are common trace constituents in zinc-rich massive sulphides and can be captured as byproducts. A 6.4-metre drill intersection that graded 4.7% zinc, 0.57% copper, 0.2 gram gold and 41 grams silver per tonne also carried 44 grams indium and 42 grams gallium per tonne.
Gross values, based on those grades and current prices, are US$44 per tonne for the indium and US$27 per tonne for the gallium. By comparison, the gold in the same intersection would contribute US$3 per tonne to gross value, and the silver, US$15.
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