Cave of the Crystals
Cave of the Crystals or Giant Crystal Cave is a cave connected to the Naica Mine 300 meters below the surface in Naica, Chihuahua, Mexico.
The main chamber contains giant selenite crystals, some of the largest natural crystals ever found. The cave’s largest crystal found to date is 12 m in length, 4 m in diameter, and 55 tons in weight.
The cave is extremely hot, with air temperatures reaching up to 58°C with 90 to 99 percent humidity. The cave is relatively unexplored due to these factors. Without proper protection, people can only endure approximately ten minutes of exposure at a time.
The cave was discovered by the brothers Eloy and Javier Delgado.
A group of scientists known as the Naica Project has been heavily involved in researching these caverns.
Naica Mine lies on an ancient fault above an underground magma chamber below the cave. The magma heated the groundwater which was saturated with sulfide ions. Cool oxygenated surface water contacted the mineral saturated heated water, but the two did not mix due to the difference in their densities.
The oxygen slowly diffused into the heated water and oxidized the sulfides into sulfates. The hydrated sulfate gypsum crystallized at an extremely slow rate over the course of at least 500,000 years forming the enormous crystals found today. The key to this process is the slow diffusion of oxygen from the cool, low-density surface water into the hot, high-density groundwater.
In 1910 miners discovered a cavern beneath the Naica mine workings, the Cave of Swords. It is located at a depth of 120 m, above the Cave of Crystals, and contains spectacular, smaller, just 1 m long, crystals. It is speculated that at this level, transition temperatures may have fallen much more rapidly, leading to an end in the growth of the crystals.
Giant Crystal Cave was discovered in April of 2000 by miners excavating a new tunnel for the Industrias Peñoles mining company located in Naica, Mexico while drilling through the Naica fault, which they were concerned would flood the mine. The mining complex in Naica contains substantial deposits of silver, zinc, and lead.
The Cave of Crystals is a horseshoe-shaped cavity in limestone. Its floor is covered with perfectly faceted crystalline blocks. Huge crystal beams jut out from both the blocks and the floor. The caves are accessible today because the mining company’s pumping operations keep them clear of the water.
If the pumping were stopped, the caves would again be submerged in water. The crystals deteriorate in air, so the Naica Project is attempting to visually document the crystals before they deteriorate further.
Two other smaller caverns were also discovered in 2000, Queen’s Eye Cave and Candles Cave, and a further chamber was found in a drilling project in 2009.
The new cave, named Ice Palace, is 150 m deep and is not flooded, but its crystal formations are much smaller, with small ‘cauliflower’ formations and fine, thread-like crystals.
All of the caves discovered currently are Cave of Crystals, Queen’s Eye, Candles Cave, Ice Palace, and Cave of Swords.
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 extreme temperature and humid conditions which prevent prolonged incursion in the crystal chamber, they developed their own refrigerated suits and cold breathing systems.
Special caving overalls were fitted with a mattress of refrigerating tubes placed all over the body and connected to a backpack weighing about 20 kg containing a reservoir filled with cold water and ice. The cooling provided by melting ice was sufficient to provide about half an hour of autonomy.
Besides mineralogical and crystallographic studies, biogeochemical and microbial characterization of the gypsum giant crystals were also performed. According to the performed uranium-thorium dating to determine the maximum age of the giant crystals, about 500,000 years.
The cave was featured on the Discovery Channel program Naica: Beyond The Crystal Cave in February 2011. Exploration has given credence to the existence of further chambers, but further exploration would have required significant removal of the crystals.
As the cave’s accessibility is dependent on the mine’s water pumps when mineral exploitation is ended in the area it is likely the pumps will be shut off and the cavern’s water level allowed to rise again.