Gold Fields is set to buy Osisko Mining for $1.57 billion, giving the South African company full control of the Windfall project in Canada.

Under the deal Gold fields is offering 4.90 Canadian dollars in cash for each Osisko share held. The price is a 67% premium to its closing price of 2.94 Canadian dollars on Friday.

"Over the past two years, beginning with our initial due diligence in 2022 and throughout our joint ownership of the Project since May 2023, we have developed a strong understanding of Windfall and its potential, and view it as the next long-life cornerstone asset in our portfolio," Gold Fields Chief Executive Mike Fraser said Monday.

Windfall is expected to produce around 300,000 ounces of gold a year at an all-in sustaining cost of $758 an ounce, Gold Fields said.

It added that environmental permitting for full-scale construction of the project is underway, with a new round of questions recently received from the Quebec Ministry of the Environment, and final approval expected in 2025.

The company said it expects the deal to close in the fourth quarter of this year.