Uncovering those minerals threatens to hasten their demise.
- Laura Millan Lombrana
Government geologist Gino Casassa steps down from the helicopter and looks around in dismay.
Casassa is standing at the foot of a glacier, 4,200 meters (13,800 feet) above sea level.
The sky over the Andes is a deep blue, but something is not right: It’s July—mid-winter in South America—and yet it’s mild for the time of year, above 0 degrees Centigrade.
He takes off…