That Rio Tinto (NYSE: RIO) is selling its stake in the massive Simandou iron project isn’t really much of a surprise. All through the year, the miner has been paving the way for the sale of the project in southeastern Guinea, first by writing down virtually the entire value of its $2 billion investment in the project, leaving just $10 million in carrying value on the books, and then by officially putting it into mothballs this summer.