10 Giant crystal cave in Nacia, Mexico. The cave is 950 feet (290 meters) underground. The Naica mining complex, which yields lead, zinc, copper, silver, and gold, zigzags nearly half a mile underground (760 meters). Pages: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
