Located in the south of Chihuahua in Mexico, the Cave of the Crystals or Giant Crystal Cave, locally known as Cueva de los Cristales, was lying deep inside the earth since time unknown. The cave was discovered only in 2000, when two miners in search of traces of silver, broke into the extensive subterranean chamber. In fact, the cave is made up of three co-joined caves, one of which is far larger than the others.
Ninety years after the discovery of the ‘Cave of Swords’, a group of miners working on an excavation tunnel for the Industrias Peñoles Mining Company, discovered another, much larger cave, 300 meters below the Earth’s surface. The entire cave was under water and it was exposed, when the water was pumped out. It was a magical discovery, since it contains the largest crystals on the planet. The Crystal cave or Cueva de los Cristales, is also known as the ‘Superman Cave’ as it looks like the Arctic home of the comic book series of Superman. The cave is a 80 meter hallway filled with gigantic gypsum crystals, up to two meters in length. The largest crystal found inside the cave is 12 meters (39 feet) in length, 4 meters (13 feet) in diameter and 55 tons in weight. Scientists believe that this gigantic crystal has been growing inside the cave for over 500,000 years.
The crystals took ages to grow into gigantic sizes. The present size of the gypsum selenite crystals was formed due to the hydrothermal fluids emanating from the underground magma chambers, several years ago. For millions of years, groundwater saturated with calcium sulfate, filtered through the caves at Naica, and then warmed by the tremendous heat from the magma below. As the magma cooled, water temperature inside the caves slowly stabilized at about 136°F. At that ideal temperature minerals mixed in the water started the process of converting themselves to selenite, molecules of which were laid down like small pieces of bricks to form crystals. Over the course of at least 500,000 years, the selenites (hydrated sulfate gypsum) crystallized at an extremely slow rate, forming the huge crystals found today. Though it may seem ridiculous, the size of the crystals has no limit and given enough time will grow to even larger proportions.
Inside the cave, there are towering crystals looking like glittering beams, lots of fallen obelisks and pillars of unearthly light. Clusters of smaller crystals are abundant on the floor and walls, which are sharp as blades and flawlessly transparent. However, with air temperatures that reach up to 58°C and humidity that ranges from 90 to 100 percent, getting inside the cave is definitely not very amusing. The scientists and the researchers are, therefore, required to wear special cooling suits along with an oxygen supply and even then, can spend no longer than 30-45 minutes within the cave.
Till date, apart from Cave of Crystals, four other crystal caves are discovered - Queen's Eye, Candles Cave, Ice Palace and Cave of Swords. The caves, including the shallowest Cave of Swords, are completely closed to visitors, due to the risk to both crystals and tourists. There are very few places in the world, where such special areas have been so well preserved in their purest natural conditions.