DENVER (AP) â¿¿ Gold producer Newmont Mining Corp. said Monday that CEO Richard O'Brien will step down on March 1 and be replaced by the company's chief operating officer, who was recruited just a year ago. Gary Goldberg, 53, who is also Newmont's president, will also join the board of directors. Newmont shares fell 83 cents, less than 2 percent, to $46.26 in midday trading. Through Friday, the shares had fallen 21.5 percent for the year. Goldberg left Rio Tinto PLC, where he had spent 30 years, including as CEO from 2006 to 2011, to join Newmont in December 2011 as executive vice president and chief operating officer. He was promoted to president in July. Goldberg was chairman of the National Mining Association from 2008 to 2010. O'Brien, 58, has been Newmont's CEO for five years. He endorsed Goldberg's selection and said they will work together on the transition. O'Brien will retire from the Newmont board.