While Northern Star will not be a partner in Windfall, Osisko maintains it will continue a cordial and beneficial relationship with the Australian company, which is an important debt holder having advanced a C$154 million convertible senior unsecured debenture due Dec. 1, 2025, with an interest rate of 4.75% per annum.
In January, Osisko released its latest resource estimate for Windfall gives the project a total of 6.8 million oz. gold. Using a gold cut-off grade of 3.5 g/t, Windfall has 9.5 million measured and indicated tonnes, averaging 10.5 g/t gold (3.2 million oz. of gold) and 5.2 g/t silver (1.6 million oz. of silver). The indicated resource is another 13 million tonnes at 8.6 g/t gold (3.6 million oz. of gold) and 4.7 g/t silver (2 million oz. of silver).
Windfall is the largest high-grade gold project with multi-million-ounce resources, based on the latest resource update.
Since that time, the company continues to drill wide, high-grade intersections. Selected intercepts released last month include 482 g/t gold over 3.7 metres, 380 g/t over 3.2 metres,143 g/t over 3.4 metres, 87.9 g/t over 3.2 metres, and more.
A new high-grade zone has been discovered at the Golden Bear target about 1 km north of the Windfall deposit. Assays included 15.3 g/t gold over 3.5 metres, 6.26 g/t over 2.8 metres, 4.14 g/t over 1.4 metres, 4.15 g/t over 1.2 metres, and 10.5 g/t over 2.4 metres.
Osisko is also conducting an infill drill campaign in the high-grade Lynx zone prior to bulk sampling. Results from this work were released earlier this month. They assayed uncut grades of 696 g/t gold over 43.4 metres, 193 g/t over 2.3 metres, 248 g/t over 2.2 metres, 72 g/t over 5.1 metres, down to 7.04 g/t over 3 metres.
A preliminary economic assessment for Windfall published in April 2021 outlined a 235,000 to 328,000 oz. per year mine with a life of 18 years. Preproduction construction costs would be C$543 million, followed After-tax payback after the start of production would take 2.2 years.
The after-tax net present value with a 5% discount would be C$1.5 billion and the internal rate of return 39.3%. The project could generate gross revenues pf C$8.2 billion or operating cash flows of C$2.6 billion over its lifetime. During production, the mine and mill would employ about 400 workers.
(This article first appeared in the Canadian Mining Journal)
