Measured and indicated resources are up 73% to 3.2 million ounces, with the average grade increasing by 9% to 10.5 grams per tonne gold.

Windfall also has an inferred resource of 3.6Moz at 8.6gpt gold, an 8% increase in grade.

About 60%, or 4.1Moz of the total resource, is contained within the Lynx deposit.

"The world-class Windfall deposit continues to impress with grade and scale," Osisko CEO John Burzynski said.

"This MRE forms a strong foundation for the upcoming feasibility study. We are confident that as we complete the remaining infill work in the coming months, the resource will continue to grow and we should again see incremental increase in what is already a strong average grade."

Osisko took out the title of the world's best drill hit of 2021, according to Opaxe, for the second year running for a Windfall hit of 2.3m at 3979gpt gold from 535.8m, reported in October.

The company has completed an additional 700,000m of drilling since September 2021.

The feasibility study is due to be completed by the end of the year.

"Windfall is an outstanding, well-defined deposit which still has demonstrable strong upside potential to grow," Burzynski said.

Last month, Northern Star Resources subscribed for a C$144 million convertible senior unsecured debenture in Osisko and has been granted an exclusive right to negotiate to acquire up to a 50% interest in Windfall.

An April 2021, preliminary economic assessment outlined a $544 million operation to produce 300,000oz of gold per annum in the first seven years of an 18-year operation at all-in sustaining costs of US$610 per ounce.

The study returned a post-tax internal rate of return of 39.3%, net present value of C$1.5 billion and payback period of 2.2 years.

Argonaut Securities analyst John Macdonald noted the rise in Osisko's share price since Northern Star invested.

On December 1, Osisko had a C$2.93 share price, and a market capitalisation of $1.04 billion, which had increased to $3.55 and $1.24 billion respectively as of this morning.