Pistol Bay Mining Inc. and Rio Tinto unit Rio Tinto Exploration Canada Inc. amended the option agreement over Pistol Bay's C4, C5 and C6 uranium properties in Saskatchewan.
Rio Tinto has earned a 75% interest in the assets and announced its intention to exercise the option to acquire a 100% stake.
Under the amended terms, Rio Tinto can acquire the remaining 25% interest by paying Pistol Bay an initial C$750,000 by April 17.
It will also be required to pay either C$1.5 million by Dec. 31, C$2 million by Dec. 31, 2018, or C$2.3 million by Dec. 31, 2019.
Pistol Bay will retain a 5% net profits interest in the property, according to a March 28 release.
Earlier Rio Tinto was required to pay Pistol Bay C$5 million by Dec. 31, 2019, to take its stake in the C block of properties to 100%.
In January, Rio Tinto informed Pistol Bay that it will continue its exploration program on the 2,500-acre C5 property.