One unseasonably warm weekend in March, executives from some of the largest Western mining firms moped around a convention center in Toronto, Canada. The glum atmosphere was a stark contrast to the much more celebratory feel of mining conferences in recent years. Just three years ago, Robert Friedland, the eccentric founder of Ivanhoe Mines, told mining executives that they were about to “make more money” than ever before: After decades of being shunned as a dirty industry best kept offshore