China Molybdenum paid Rio Tinto US $820 million to gain control of its stake in a copper-gold mining project in New South Wales. The transaction was touted to be the biggest in the industry so far this year.

Chris Lynch, CFO of Rio Tinto, dismissed suspicions that the Northparkes is losing, which became the main motivation for the decision to sell. "Northparkes is a successful business but is not of sufficient size to be a good fit with our strategy," he said. 

The deal, however, could not be completed without the approval of Rio's partner Sumitomo Corp. The said company should first waive its right to tender an offer matching the bid. Prior to the announcement, Rio already sold its stake from another mining project for US $325 million.

Sam Walsh, Rio's chief executive, said this is part of their overall strategy to limit their attention to core business and get "significant cash proceeds" by selling non-core operations.