It is considered the world's highest-grade rare earth mine, and has cleared the last permit needed to move forward.

The company is seeking access to Obuasi’s 30-million-ounce ore body over the next two decades.

The levy on gemstones, excluding diamonds, was meant to increase the country's revenues, but ended up hitting output.

Top executives at the world's largest mining companies expect a big focus on environmental, social and governance issues and more consolidation.

Average price per carat was $548, 16% more than expected and about 40% higher than the average price achieved in the previous quarter.

It fetched $425 million for its diamond in December, a slight improvement from the $400 million it obtained in the previous sale.

News comes at a difficult time for Zimbabwe, with its economy forecast to contract 6.5% this year because of crippling foreign-currency, fuel, wheat and power shortages.