Crystal Cave of Giants in Mexico
from Crystalinks Website

The Naica Mine of Chihuahua, Mexico, is a working mine that is known for its extraordinary crystals. Naica is a lead, zinc and silver mine in which large voids have been found, containing crystals of selenite (gypsum) as large as 4 feet in diameter and 50 feet long. The chamber holding these crystals is known as the Crystal Cave of Giants, and is approximately 1000 feet down in the limestone host rock of the mine. The crystals were formed by hydrothermal fluids emanating from the magma chambers below. The cavern was discovered while the miners were drilling through the Naica fault, which they were worried would flood the mine. The Cave of Swords is another chamber in the Naica Mine, containing similar large crystals.

The Naica mine was first discovered by early prospectors in 1794 south of Chihuahua City. They struck a vein of silver at the base of a range of hills called Naica by the Tarahumara Indians. The origin in the Tarahumara language seems to mean "a shady place". Perhaps here in the small canyon there was a grove of trees tucked away by a small canyon spring.

From that discovery, until around 1900, the primary interest was silver and gold. Around 1900 large-scale mining began as zinc and lead became more valuable.

During the Mexican Revolution the mine was producing a great deal of wealth. Revolutionary troops entered the town and demanded money from the owners. One of them was assassinated when he refused to pay, causing the mine to shut down from 1911 to 1922.

Just before the mine was closed, the famous Cave of Swords was discovered at a depth of 400 feet. Due to the incredible crystals, it was decided to try to preserve this cave. While many of the crystals have been collected, this is still a fascinating cave to visit. In one part there are so many crystals on one of the walls, they appear to be like an underwater reef moving in a gentle undulating motion in an ocean current.

In April 2000, brothers Juan and Pedro Sanchez were drilling a new tunnel when they made a truly spectacular discovery. While Naica miners are accustomed to finding crystals, Juan and Pedro were absolutely amazed by the cavern that they found. The brothers immediately informed the engineer in charge, Roberto Gonzalez. Ing. Gonzalez realized that they had discovered a natural treasure and quickly rerouted the tunnel. During this phase some damage was done as several miners tried to remove pieces of the mega-crystals, so the mining company soon installed an iron door to protect the find. Later, one of the workers, with the intention of stealing crystals, managed to get in through a narrow hole. He tried to take some plastic bags filled with fresh air inside, but the strategy didn't work. He lost consciousness and later was found thoroughly baked.

When entering the cave our group is issued helmets, lanterns, rubber boots, and gloves. One must then be driven by truck into the main mining tunnel called Rampa Sn. Francisco. While the vertical drop is approximately 1000 feet, the drive is almost a half mile long. The heat steadily increases and women have been observed to begin "glowing". The truck stops in front of a concrete wall with a steel door. The intense heat can prevent brain functioning.

At the end of the tunnel there are three or four steps into the aperture of the cavern itself. It is in this short tunnel. In this short distance the temperature and humidity goes from being uncomfortably warm to literally a blast furnace.

Momentarily, the penetrating heat is forgotten as the crystals pop into view on the other side of the "Eye of the Queen". The entire panorama is now lighted and the cavern has a depth and impressive cathedral-like appearance that was not visible on earlier trips with just our headlamps.

When inside the great cathedral of crystals, the pressure of intense heat create a gamut of emotions and perhaps hallucinations. One can only remain for a short period of time.

Geologists report that these natural crystal formations are incredibly complex, yet so simple. They have a magical or metaphysical personality independent of their chemical structures. There is a magma chamber two to three miles below the mountain and that heat from this compressed lava travels through the faults up into the area of the mine. Super heated fluids carry the minerals the miners are seeking as well as form the crystals. The mine is ventilated; otherwise, it could not be worked. Some parts, however, are not air-conditioned, such as the Cave of the Crystals, and there you feel the heat from the magma deep below. The fluids travel along the Naica fault, enter voids in the bedrock, and then form entirely natural structures that are not easily explained scientifically.

In April 2000, the mining company became confident that the water table on the other side of the fault had been lowered sufficiently to drill.

When they did this, it is almost as if a magical veil of reality was breached and an entirely new world was discovered. Two caverns filled with the Earth's largest crystals were immediately revealed. More discoveries are expected to be made in this magical kingdom of intense natural beauty.

Selenite, the gypsum crystal, named after the Greek goddess of the moon, Selene, due to its soft white light, is said to have many metaphysical and healing benefits. Selenite powder has been used cosmetically for thousands of years to enhance one's natural beauty. It is believed that this crystal assists with mental focus, growth, luck, immunity, and soothes the emotions.

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Giant Crystal Cave's Mystery Solved National Geographic

by Stefan Lovgren
for National Geographic News

April 7, 2007

from NationalGeographic Website

It's "the Sistine Chapel of crystals," says Juan Manuel García- Ruiz. The geologist announced this week that he and a team of researchers have unlocked the mystery of just how the minerals in Mexico's Cueva de los Cristales (Cave of Crystals) achieved their monumental forms.


Buried a thousand feet (300 meters) below Naica mountain in the Chihuahuan Desert, the cave was discovered by two miners excavating a new tunnel for the Industrias Peñoles company in 2000. The cave contains some of the largest natural crystals ever found: translucent gypsum beams measuring up to 36 feet (11 meters) long and weighing up to 55 tons.

"It's a natural marvel," said García-Ruiz, of the University of Granada in Spain.

To learn how the crystals grew to such gigantic sizes, García-Ruiz studied tiny pockets of fluid trapped inside. The crystals, he said, thrived because they were submerged in mineral-rich water with a very narrow, stable temperature range—around 136 degrees Fahrenheit (58 degrees Celsius). At this temperature the mineral anhydrite, which was abundant in the water, dissolved into gypsum, a soft mineral that can take the form of the crystals in the Naica cave.

The new findings appear in the April issue of the journal Geology.

Volcanic Activity
The mining complex in Naica contains some of the world's largest deposits of silver, zinc, and lead. In 1910 miners discovered another spectacular cavern beneath Naica. Its walls studded with crystal "daggers," the Cave of Swords is closer to the surface, at a depth of nearly 400 feet (120 meters).

While there are more crystals in the upper cave, they are far smaller, typically about a yard (a meter) long.

Nearly the Size of a Basketball Court
The Cave of Crystals is a horseshoe-shaped cavity in limestone rock about 30 feet (10 meters) wide and 90 feet (30 meters) long. Its floor is covered in crystalline, perfectly faceted blocks. The huge crystal beams jut out from both the blocks and the floor.

"There is no other place on the planet where the mineral world reveals itself in such beauty," García-Ruiz said.

Volcanic activity that began about 26 million years ago created Naica mountain and filled it with high-temperature anhydrite, which is the anhydrous—lacking water—form of gypsum. Anhydrite is stable above 136 degrees Fahrenheit (58 degrees Celsius). Below that temperature gypsum is the stable form.

When magma underneath the mountain cooled and the temperature dropped below 58 degrees Celsius, the anhydrite began to dissolve. The anhydrite slowly enriched the waters with sulfate and calcium molecules, which for millions of years have been deposited in the caves in the form of huge selenite gypsum crystals.

"There is no limit to the size a crystal can reach," García-Ruiz said.

But, he said, for the Cave of Crystals to have grown such gigantic crystals, it must have been kept just below the anhydrite-gypsum transition temperature for many hundreds of thousands of years.

In the upper cave, by contrast, this transition temperature may have fallen much more rapidly, leading to the formation of smaller crystals.

To Reflood or Not to Reflood
While the chance of this set of conditions occurring on other places in the world is remote, García-Ruiz expects that there are other caves and caverns at Naica containing similarly large crystals.

"The caves containing larger crystals will be located in deeper levels with temperatures closer to, but no higher than, 58 degrees Celsius," he said.

He has recommended to the mining company that the caves should be preserved. The only reason humans can get into the caves today, however, is because the mining company's pumping operations keep them clear of water. If the pumping is stopped, the caves will again be submerged and the crystals will start growing again, García-Ruiz said.

So what happens if—or when—the mine is closed?

"That's an interesting question," García-Ruiz said.


"Should we continue to pump water to keep the cave available so future generations may admire the crystals? Or should we stop pumping and return the scenario to the natural origin, allowing the crystals to regrow?"

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Giant Crystals Enjoyed Perfection

April 6, 2007

from BBCNews Website

With lengths over 11m, the giant gypsum crystals found in Mexico's Cueva de los Cristales are a great natural wonder

The cave was discovered in 2000


Now, a Spanish-Mexican team thinks it can explain how these marvels acquired their immense form. The scientists studied tiny pockets of fluid trapped in the crystals and conducted back-up lab experiments. They report in the journal Geology that the solution from which the crystals grew must have been kept in a very narrow, stable temperature range.

The researchers' analysis leads them to believe there are other dramatic caves waiting to be discovered in the Naica mine complex south-east of Chihuahua city.

"If the theory we propose for the 'genetic' mechanisms of the crystals is right, then I would not be surprised if miners find more of these caves in the next few years," Juan Manuel Garcia-Ruiz, from the University of Granada, Spain, told BBC News.

Bigger than 'swords'
Already two remarkable caves are known at Naica, which has yielded some of the world's most significant deposits of silver and lead. The 120m-deep Cueva de las Espadas (Cave of Swords), discovered in 1912, is named for its meter-long shafts of gypsum (a calcium sulphate mineral that incorporates water molecules into its chemical formula). And although individually there are fewer crystals in the 290m-deep Cueva de los Cristales, its beams are considerably bigger.

Professor Garcia-Ruiz and colleagues believe they can now show how these differences emerged. The team studied tiny fluid samples embedded inside the crystals themselves. These watery inclusions record tell-tale chemical details of the saline and temperature conditions of the saturated solution from which the mammoth structures developed.

'Perfect conditions'
Both caves owe their origin to the volcanism which laid down the metal sulphides - the ores - that have proved so valuable. Copious amounts of calcium sulphate would also have been created towards the end of this mineralization process more than 20 million years ago - but in the hot fluids that infused the cracks and cavities in the rock, this calcium sulphate would have taken the form of anhydrite.

Anhydrite has the same chemical formula as gypsum, except that it excludes water. Only as the magma chamber deep under the Naica mountain cooled did the hot fluids above start to fall to a temperature at which anhydrite could switch to gypsum.

Professor Garcia-Ruiz and colleagues say their studies indicate that the deeper of the two caves - Cueva de los Cristales - must have been kept just below the transition temperature for many hundreds of thousands of years.

"The conditions were perfect. By maintaining the temperature just below 58 degrees for a very long time you get a few, very big crystals," said Professor Garcia-Ruiz.

"You can see that many areas on the cave's walls are empty; they have no crystals. The walls are red because of the iron oxide. The reason we know this happened for many years is because we studied the fluid inclusions inside the crystals."

It is likely the upper cave - Cueva de las Espadas - fell below the transition temperature much more rapidly and consequently grew many, smaller crystals.

Heritage future?
The particular crystalline form taken by the gypsum is selenite which is known for its translucency. Their future will be dependent on the fate of the mine. At the moment, access is restricted to prevent damage to the soft crystals. And humans can only get in the caves at all because of the continuous pumping operations that keep them clear of water.

If, when Naica's ores are no longer viable, the mine is closed and the pumping is stopped, then the caves will be submerged - and the crystals will start growing again.

"I've recommended to the mining company that they try to preserve them and I would like to see Unesco get involved," explained Professor Garcia-Ruiz.

"Later on we should decide whether to keep them available for people to visit and enjoy, or let the natural scenario return."

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Largest Crystals Found in Mexico

Discovery News

February 8, 2001

from TheCrystalPortal Website

The largest natural crystals on Earth have been discovered in two caves within a silver and zinc mine near Naica, in Chihuahua, Mexico, according to mine officials. Reaching lengths of over 20 feet, the clear, faceted crystals are composed of selenite, a crystalline form of the mineral gypsum.

"Walking into either of these caves is like stepping into a gigantic geode," said Richard D. Fisher, an American consultant with the mining company to develop the discoveries as tourist attractions.

Fisher said that most people can endure only a few minutes in the caves due to their high temperatures. The smaller of the two, which is about the size of two-bedroom apartment, is 100 Fahrenheit. The large chamber, which Fisher describes as the size of a Cathedral, is 150 F. Both are located approximately 1200 feet below the surface. The mining company plans to air-condition the caves before opening them to the public next year, Fisher said. He adds that reducing the heat gradually will not harm the crystals.

The largest previously known crystals were found in the nearby "Cave of the Swords", part of the same mine system. Some of these are now on display at the Smithsonian Institution. The local government and mine owners hope to avoid removing any of the new discoveries for museum displays or private collections, Fisher said.


While the mine company is currently limiting visitation of the caves to scientific experts, mineral hunters have destroyed locks and broken into the chambers twice since they were first opened by mining equipment last April. One man was killed when he attempted to chop out a gigantic crystal that fell from the ceiling and crushed him, according to Fisher.

"We need more onsite protection of mine caves," said geologist Carol A. Hill, co-author of the book Cave Minerals of the World, who calls the new discoveries "by far the largest selenite crystals I have ever heard of."

Hill applauds the tourism plan.

"Without it, the mining company would probably destroy the caves. Museums have enough crystals," she said. "It's important to preserve discoveries like this where they occur."

Fisher and mine officials will display photographs and small samples of crystals from the new cave at the Tuscon Gem & Mineral Show in Arizona - which starts today and runs through the weekend - where they plan to organize a scientific study of the caves to take place in March.



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Cristales Gigantes de Selenita

del Sitio Web MineralTown

Cuevas de cristal de Naica
Profundamente debajo de la superficie de un aislado sistema montañoso en Méjico descansan dos espacios de esplendor: los cristales translúcidos de longitud y circunferencia como árboles de pino adultos descansan echados uno encima de otro, como si los rayos de luna tomaron repentinamente peso y sustancia.

En abril de 2000, los hermanos Eloy y Javier Delgado encontraron lo qué los expertos creen que son los cristales aislados más grandes del mundo mientras que abrían un nuevo profundo túnel de exploración en la mina de plata, plomo y zinc de Naica de la meridional Chihuahua.


Después de descubrir una pequeña abertura cerca de 300 metros más abajo, Eloy se retorció adentro y encontró una caverna de 8 metros llena de cristales inmensos. Un mes y medio después, otro equipo de mineros de Naica les sucedió lo mismo con una caverna adyacente incluso más grande que la primera.

Los geólogos conjeturan que un compartimiento de magma, o roca fundida sobrecalentada, que se encontraba a dos o tres millas por debajo de la montaña forzó los líquidos ricos en minerales hacia arriba a través de una grieta en las aberturas en la roca de fondo de piedra caliza cerca de la superficie. Durante tiempo, quizá más de 30 millones de años, este líquido hidrotérmico depositó los sulfuros ricos en plata, plomo y zinc en la roca de fondo de la piedra caliza.


Estos metales se han minado aquí desde que los prospectores descubrieron los depósitos en 1794 en un pequeño sistema de colinas al sur de la ciudad de Chihuahua. Además, los líquidos hidrotérmicos disolvieron el yeso, el mismo material usado en cartón de yeso y el yeso de París, situado en la roca de fondo. Las soluciones calientes, ricas en mineral dieron a luz a estos cristales gigantes de selenita.

Además de columnas de 1 metro de diámetro y 15 metros en longitud, la caverna contiene fila sobre fila de formaciones diente de tiburón de hasta 1 metro de alto, que se colocan en los ángulos impares a través de la cueva. Hasta abril de 2000, los funcionarios que minaban habían restringido la exploración en un lado de la grieta fuera de la preocupación que cualquier nuevo túnel pudo conducir a inundar el resto de la mina. Solamente después que el nivel del agua había caído suficientemente autorizaron el túnel que condujo a los hermanos Sanchez al asombroso descubrimiento.

Previamente, los ejemplos más grandes del mundo de cristales de selenita vinieron de una caverna próxima descubierta en 1910 dentro del mismo complejo de la cueva de Naica. Varios ejemplos de la Cueva de las Espadas se exhiben en el Janet Annenberg Hooker Hall of Geology, Gems, and Minerals del Smithsonian's National Museum of Natural History.

Cristales gigantes de yeso en la mina Naica, Méjico


Algunos hechos y datos adicionales:

  1. El tamaño de la cueva es de casi 50m de largo por 30m de ancho. La cueva incluye cristales 1.5 m de alto con lados agudos, y cristales más grandes son como vigas más de 12m largo y 0.60m de grueso.

  2. Los hombres que descubrieron la cueva fueron los hermanos Eloy y Javier Delgado

  3. La primera cueva descubierta fue llamada Ojo de la reina, porque tiene una pequeña entrada, y se parece a un ojo humano. La primera cueva original es de 20m en longitud por un promedio de 10m ancho. Esta cueva no está todavía abierta al público.

  4. Para que los cristales se formen, deben tener dos condiciones principales - primero la formación de la cueva, y entonces la formación de los cristales.

  5. La formación de la cueva se relaciona con la circulación del agua subterránea a lo largo del sistema de grietas o de la fractura que disuelve el carbonato de calcio de la piedra caliza, y va creando una cueva.

  6. El proceso de la formación de los cristales es más complicado porque depende de la temperatura, la presión, la geoquímica y la fluctuación del acuífero dentro de la cueva. El agua termal, rica en ácido sulfúrico por la acción entre el agua y la oxidación del plomo y del sulfuro del zinc, asciende a través de las fracturas y consigue el carbonato por la disolución de la piedra caliza. Sobre la sobresaturación que alcanza la precipitación y la cristalización del sulfato de calcio comenzadas. Pensamos que el crecimiento de los cristales tomó más de 30 años si no había un cambio en las condiciones de la cueva.

  7. La exploración se está avanzando al lado de la grieta, pero estamos intentando preservar la cueva. Mi opinión personal es que tenemos más cuevas como esta sin descubrir.

  8. Estamos haciendo una investigación conjuntamente con la universidad de Granada de España y estamos haciendo pruebas de laboratorio con la UTEP de EL Paso, para intentar explicar la formación de los cristales.

  9. Vamos a hacer un proyecto de ingeniería para mantener las condiciones originales de la cueva antes de que esté abierta al público. La mina está en ambos lados de la grieta, pero se protege el área de la cueva.

  10. La cueva no tiene ninguna agua. El agua va abajo a los niveles más bajos de la mina y se bombea a la superficie. Estamos bombeando realmente 14.000 galones por minuto de agua caliente (54°C).


  11. La cueva está abierta bajo visita restringida para el público, pero por el momento sólo para científicos, geólogos, mineralogistas o cualquier persona que tiene interés en la admiración de los maravillosos cristales sin dañarlos.

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Free Standing Gypsum Crystals Up to 12 m. Size in the Naica Lead-Zinc Mine
from GiantCrystals Website

The Naica mine with its enormous gypsum crystals may well be called the "Queen of the Giant Crystal localities". Giant crystals in general are exactly this : of remarkable dimensions ! But they are not necessarily nice or esthetic in the common sense and in fact they only rarely display free growing crystals. In Naica they do!


And all what you ever imagined about giant crystals in the interior of the earth, about enormous bugs filled with glittering crystals so large, you can walk among them, comes true in Naica ! This is the place to be for the real giant crystal enthusiast and quite frankly I would be glad and honored, if I ever have the opportunity to visit this place.

Historic photo of the Cave of the Swords in the upper levels of the Naica mine
Photo Source : FOSHAG, W.F. (1927)

Though the Naica mine is no show mine, but still a working and producing lead - zinc mine owned by the Penoles Company. Continuous mining goes on since more than a century and in 1910 the first of several crystal caves was discovered in a depth of 120 m underground. This so called "Cave of the Swords" contained extraordinary large sword-like selenite (gypsum) crystals up to 2 m size.


The cave supplied large quantities of large scale specimen with magnificent "herring bone structure" selenite crystals to major mineralogical and collections world wide. It is a single huge chamber about 70m in diameter and is still accessible to geoscientists and even - as far as we know - to the public. A narrow winding path leads to the forest of crystals, which however have lost much of its luster and splendor over the decades.

In 2000 another crystal cave system was discovered at 300 m depth, even much more spectacular than the original discovery back in 1910. This newest discovery was named the "Cave of the Crystals" and it turned out to be one of the most spectacular geological and mineralogical discoveries ever made ! In fact it is a complex system of caves orientated along a geological fault, which yield free growing gypsum crystals up to 12 m size (!) and 2 m diameter.

As the initial temperature inside the caves was 60°C and the humidity 100%, a detailed exploration of the caves proved extremely difficult. There is the story about a mine worker, who tried to steal some of the magnificent crystals shortly after the initial discovery, but was overwhelmed by heat, humidity and the low oxygen content of the cave atmosphere, lost consciousness and was found literally cooked by his fellows some days later...

Giant gypsum crystals up to 12 m in the lower levels of Naica mine


That said, conditions in the caves are much more hospitable now and a lot of photos exist on the web showing cave explorers posing in T-Shirts within a maze of giant crystals. But serious exploration and documentation of the caves and the giant gypsum crystals still has its obstacles. Right now a group of Italian speleologists - the Laventa group - has started a large scale scientific mapping project, using state of the art technical equipment to tackle the still hostile environment of these caves. Please have a look here for more information of this venture including an online diary.

The discovery of the giant gypsum crystals at Naica has triggered a wealth of geological research on this subject with the first papers published only recently. For more information please visit our Reading Room.


More scientific literature is likely to be published within the near future.


The Naica gypsum crystals in a nutshell

Mineralogy :

Gypsum, possibly some sulfide minerals

Crystal Size :

mostly freestanding prismatic crystals up to 12 m

Geology & Origin :

Possibly hydrothermal replacement of limestone by sulphuric acids, more research is certainly warranted


Current status :    

Active mine, access to upper crystal caves for tourists possible, access to lower crystal caves remain restricted

Remarks :

Spectacular freely developed (!) gypsum crystals up to 12 m, possibly the largest in the world


Other notable & famous gypsum occurrences


Note: Gypsum is a very frequent mineral and even large gypsum crystals are by no means uncommon. There are however some outstanding occurrences, namely :

  • Gypsum crystals of up to 12 m or are rumored to occur at other Mexican localities such as the Caverna de Santo Domingo, Santa Eulalia district.

  • Giant clear gypsum crystals up to 7 m are known from the Debar gypsum mine Macedonia.

  • The "Gran Geoda" of the Pilar de Jaravia mine, Spain with large, clear gypsum crystals.

  • Enormous crystals of gypsum are reported from the Braden and the El Teniente Mine, Chile...possibly even the largest of the world.

  • Perfect crystals up to 1 m are known to occur in the Raura mine, Lima Department, Peru.


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