This signals a shift from Nigeria's decades-old policy of exporting raw materials.

"Gold seems to be on standby after a three-day rally with investors on the sidelines ahead of key US data," one analyst says.

It expects to produce 100,000-120,000 oz. of gold from its Tujuh Bukit mine and 14,000-16,000 tonnes of copper from its Wetar mine.

Ramelius had been looking at a potential acquisition of the Canada-based mine operator.

What the market interpreted to be an exploration miss at the Mila discovery on the Motagua Norte project turned out to help zero in on the actual gold source.

The transaction, scheduled to close in July, is expected to create $515 million in cost-savings over about two decades of production.

Much of the reason the M+I resources grew was due to reclassifying inferred material in areas immediately beyond the current reserve boundary.