|Naica Hills, south of Chihuahua City.
Cave of Swords: electric.
Cave of Crystals: none.
Cave of Swords: L=80 m, W=70 m, D=120 m, T=40 °C, H=100%.
Cave of Crystals: L=8 m, W=8 m, H=8 m, D=300 m, T=60 °C, H=100%.
Carlos Lazcano Sahagun (author), Richard Fisher (images), Margot Shackleford (2001):
Naica's Subterranean Marvels,
NSS News, June 2001, 166-169.
Juan Manuel García-Ruiz, Roberto Villasuso, Carlos Ayora, Angels Canals, Fermín Otálora (2007): Formation of natural gypsum megacrystals in Naica, Mexico, Geology, Volume 35, Issue 4 (April 2007), Geological Society of America.
Speleoresearch & Films, Etla No. 11. Colonia Condesa C.P. 06100, Tel: +52-52736998, Tel: +52-5273692.
La Venta, via Priamo Tron, 35/F, 31100 Treviso (TV), Italy, Tel: +360-3233190267, Fax: +360-422-320981 E-mail:
|As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
Please check rates and details directly with the companies in question if you need more recent info.
|early prospectors found a vein of silver at Naica.
|Santiago Stoppelli made a claim on a mine, the settlement Naica received the category pueblo.
|the formal exploitation and large scale work started.
|revolutionary troops entered the town and and demanded money.
|Cave of Swords discovered at a depth of 120 m.
|Naica received the category township.
|the Naica Mining company suspended work due to ravages of the revolution.
|mining activity was continued.
|the mine is operated by the Penoles Group
|Cave of the Crystals discovered by Juan and Pedro Sanchez.
|explored by La Venta from Italy.
|exploration ceased and geodes flooded.
The word Naica is of Tarahumara origin and means shady place. It was given to the hills, maybe because of a spring with some trees. The hills are full of minerals which made them valuable for mining. The mine produces lead, zinc, copper, silver and gold and is one of the most productive mines in Chihuahua.
In the last years the care of the environment and for minimum contamination by the present mining company gave the mine a national level of prominence. Hopefully this attitude amongst the miners may also protect the Cave of the Crystals.
This mine is not a show mine, but a still working and producing mine. It is very hot and has a huge underground well of 52 °C hot water. The air of the mine is cooled down by a ventilation system to about 40 °C, but the humidity of the air is about 100%. The topic of this page is not the mine, but two natural caverns found inside the mine.
The Cueva de las Espadas (Cave of Swords) was found in 1910 and contains extraordinary large selenite (gypsum) crystals. It is named after the crystals, which resemble swords. The natural cave is a single huge chamber about 70 m in diameter and 120 m below surface. The prismatic gypsum crystals, which are called selenite, are up to 2m long and 25 cm in diameter. The Cave of Swords is famous among geoscientists and visited very often, thus it is equipped with paths, light and ventilation. Unfortunately the habit of removing crystals for the mineralogical museums of the world deprived the cave of its best pieces. The change in the cave climate further damaged the crystals and made them dusty and opaque.
The newest discovery is the Cueva de los Cristales (Cave of the Crystals), even more spectacular than the Cave of Swords. At a depth of 300 m first, a spherical chamber of 8 m diameters filled with selenite crystals was found. The tunnel was rerouted, but soon after a second, even bigger, chamber with several big selenite crystals, 8 m long and 2 m in diameter, was found. The longest crystal is 11 m long. It was closed by a brick wall and an iron gate to protect the crystals.
As the temperature inside the cave is 60 °C and the humidity 100 %, a visit of the cave always includes a perfect steam bath. But for work in the cave, it is really problematic. First it was absolutely impossible to take any picture of the cave as cameras first steamed up, and when they reached the temperature of the cavern, the electronic was dead. The researchers developed special techniques for the temperature, but more than 10 minutes are not possible inside the cave. Typically, two or three minute visits are applicable.
A mine worker who tried to steal some crystals died in the cave: the temperature and the bad air caused dehydration, and after a few minutes he was too weak to leave the cave and suffocated. When he was found, his body was cooked (well done to be exact).
The exploration is done by La Venta, an Italian group of cave explorers, and a Méxican company named Speleoresearch & Films. They have an agreement with the mining company Industrias Peñoles about the protection of the cave. The technical difficulties of the exploration are immense, and so far the total size of the cave is still unknown, as it is impossible to explore more than a few tens of meters in the available time. Special breathing and protection systems are developed with the goal to stay inside the cave for at least one hour.
The formation of the large selenite crystals was explored during the last years by Juan Manuel Garcia-Ruiz from the University of Granada in Spain and others. The results were published in the April 2007 issue of the journal Geology of the Geological Society of America. They determined the exact conditions of the crystal growth by analyzing the water contained in tiny pockets inside the crystals. They grew in gypsum rich water at about 58 °C, heated by the volcanic activities below.
UPDATE: The mining at the Naica mine has come to an end in 2017, further mining would have destroyed the crystal caves, due to the enormous temperatures a touristic use was not possible. As a result the mine was abandoned, the pumps turned off, and the mine has filled again with hot water. As a result none of the caves is accessible any more. On the other hand, they are back to natural conditions and protected.