El Indio, Chile. A geologist makes field observations from a vantage point overlooking an extensive mineralized zone in the Chilean Andes Mountains. He sights through a Brunton compass with the tools of his trade beside him: rock hammer, aluminum clipboard, colored pencils and map. Smoke and dust issues from an explosion on the producing surface of the open-pit mine. Haulage roads access a labyrinth of underground tunnels and shafts which explore and define the ore-body being mined. Prospecte