Ivanhoe Mines' (IVN) long tortuous quest to develop a big copper and gold field in Mongolia took another ambiguous turn Thursday.Investors, who had bid Ivanhoe stock up 60% since June in anticipation of an official deal between the mineral explorer and the Mongolian government, sold off the company's New York-listed shares in frantic trading Thursday. The stock closed the session down 14% to $7.27 on volume of 10.5 million shares, nearly ten times the daily average. Ivanhoe has been awaiting governmental clearance from Mongolia to develop the deposit, dubbed Oyu Tolgoi. The financial prospects of the Vancouver, B.C., outfit rest squarely on its success there. As an exploration company, it has no cash flow, and its bets lie on Oyu Tolgoi and little else. Approval for the project would trigger an investment in Ivanhoe by Aussie mining giant Rio Tinto ( RTP). Though Mongolia's parliament did vote in favor of Ivanhoe going forward with the project by a vote of 63%, the company said in a statement that it was "reviewing the provisions of the resolution" presented by legislators, a process that would further delay any ribbon cutting, investors worried. Many of them appeared to back away from the stock Thursday. "It's shaken investor confidence and triggered the selloff," said Mike Bellafiore, a partner at the trading firm SMB Capital. Ivanhoe officials didn't immediately return a call seeking comment.