Imagine a cave big enough to drive a car through and full of massive, magical crystals.
Located in the Mexican state of Chihuahua, in the municipality of Saucillo, the Naica mine is a working mine that is best known for its gigantic selenite crystals. Workers who dig the Naica mine produce lead (the mine is Mexico's biggest lead producer), zinc and silver. 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.
How did the crystals form?
The mine lies on top of an undergrown magma table. The heat warms the ground water in the caves, which become saturated with minerals, including large quantities of gypsum. After letting this mineral-rich hot water remain still and stable at 50 °C (122 °F) for about 500,000 years. This allowed crystals to form and grow to immense sizes.
Scientific studies of the Naica mine
Modern-day mining operations exposed the natural wonder by pumping water out of the 30-by-90-foot (10-by-30-meter) cave, which was found in 2000 near the town of Delicias.
A scientific team coordinated by Paolo Forti, specialist of cave minerals and crystallographer at the University of Bologna (Italy) explored the cave in detail in 2006. To survive and to be able to work in the dangerous conditions and extreme temperature which prevent prolonged incursion in the crystal chamber, they developed their own refrigerated suits and cold breathing systems. Scientists set up a suit with refrigerating tubes and connected to a backpack filled with ice and cold water, which would filter chilled air through the tubes. The packs weigh about 20 kg (44 lbs) and allowed about a half hour of exploration.