The Naica Mine, Mexico

The Naica Mine of the Mexican state of Chihuahua is a working mine that is best known for its extraordinaryselenite crystals.Located in Naica in the municipality of Saucillo, the Naica Mine is a lead, zinc and silvermine operated by Industrias Peñoles, Mexico's largest lead producer Caverns discovered during mining operations contain crystals of selenite (gypsum) as large as 4 feet (1.2 m) in diameter and 50 feet (15 m) long.