Buried 1000 feet below the Naica mountain in the Chihuahuan Desert, Mexico’s Cueva de los Cristales — known as the Crystal Cave of Giants — is a magnificent natural wonder of the largest crystals of selenite (gypsum) on Earth, up to 4 feet in diameter and 50 feet long, weighing as much as 55 tons. Two miners excavating a new tunnel through the Naica fault made the spectacular discovery in 2000.

The crystals were formed by hydrothermal fluids emanating from the magma chambers below. The Cave of Swords is another chamber in the Naica Mine, containing similar monumental crystals.

The Naica mine was first discovered by early prospectors in 1794 south of Chihuahua City when they struck a vein of silver at the base of a range of hills called Naica by the Tarahumara Indians.

The renowned Cave of Swords was discovered just before the closure at a depth of 400 feet. Due to the incredible crystals, it was decided to try to preserve the cave. In one part there are so many crystals on one of the walls, they appear like an underwater reef moving in a gentle undulating motion in an ocean current.

n April 2000, brothers Juan and Pedro Sanchez were drilling a new tunnel when they discovered the cave and informed the engineer in charge, Roberto Gonzalez. Gonzalez realized that they had discovered a natural treasure and quickly rerouted the tunnel. Some damage was done during this phase as several miners tried to remove pieces of the mega-crystals, so the mining company installed an iron door to protect the find.