Osisko Gold Royalties (OR.TO) said Monday that it completed an amendment to increase its silver stream on Taseko Mines' (TKO.TO) Gibraltar copper mine in British Columbia.

Under the amended terms, Osisko's attributable silver percentage rose by 12.5% to 100% while the step-down silver delivery threshold was extended to 6,811,603 ounces delivered, accounting for Osisko's additional silver ownership.

In exchange for these amendments, Osisko paid an additional deposit amount of US$12.7 million to Taseko.

Osisko's share price traded 1.2% lower at US$18.08 at last look in NYSE pre-market trading.

Osisko said the amendments were concluded following Taseko's announcement in March that it had entered into a definitive agreement to consolidate a 100% interest in Gibraltar by acquiring the remaining 12.5% interest from Dowa Metals & Mining and Furukawa.

"Osisko's shareholders will benefit from the increased silver stream from a producing mine thanks to a transaction that is consistent with our strategy of adding cash flow from long-life assets in Tier 1 mining jurisdictions," said Jason Attew, Osisko's president and CEO.

Meanwhile, Osisko announced the successful closing of its transaction to acquire a 1.8% gross revenue royalty (GRR) on Spartan Resources' Dalgaranga gold project in Western Australia for US$44 million.

Osisko also closed a complementary transaction to acquire a 1.35% GRR on additional regional exploration licenses near Dalgaranga for US$6 million.