Raul Manriquez drops a pebble in a hole in the ground. We count the seconds until we hear the impact: eight. This exploration hole is about 700 feet deep, he estimates. There are 588 more holes around us in the Sierra la Laguna mountain in Mexico. We are standing on top of what could soon be a gold mine: an estimated 1.7 million ounces of gold worth more than $2 billion are embedded in the rocks under our feet. If state officials in Baja California Sur approve the project, the hills we are standing on will be turned inside out and become one vast open pit mine.