A Zimbabwe-Russia joint venture company, Ruschrome Mining, plans to invest $1.6 billion in developing a platinum mine and constructing a smelter and refinery in the African state, the state-owned Herald newspaper reported on Tuesday, Reuters reported. Zimbabwe holds the world's second-largest known platinum deposits and two of the biggest producers of the metal, Anglo American Platinum and Impala Platinum Holdings , have operations there. The state Zimbabwe Mining Development Corporation and a consortium of Russia's Vi Holding, defence conglomerate Rostec and Vnesheconombank, jointly own Ruschrome. The Herald, which reflects government policy, quoted mines minister Walter Chidhakwa as saying the parties would sign an agreement in Harare next month, with mining operations scheduled to start early next year. The first phase of the deal would include developing the mine and constructing a concentrator at a cost of $500 million, while a platinum refinery would be built in the final phase. "The base metals and precious metal refinery is something that we are still in the process of finalising," Chidhakwa told the newspaper.