Cave of the Crystals

Rich finds of silver were discovered in the Naica mountains in the middle of the dry, inhospitable Chihuahua Desert in the 18th century. Later it was discovered that the mine had other valuable metals – zinc and lead.

Now Naica mines are the largest in Mexico and since the 1950s are managed by the company Industrias Peñoles. Ore of metals almost vertically goes down and thus the mines also are becoming deeper and deeper.

Currently, the deepest shafts are more than 850 meters deep.

Geological history

Naica Mines have formed in an ancient fault line above the magma chamber. Magma causes the high temperature in the cave but it also has formed the minerals of Naica Mine including the giant crystals.

The heated groundwater here dissolved surrounding rocks and became saturated with sulfide ions. This overheated solution went upwards until it met with the cool groundwater from the surface – this groundwater was saturated with oxygen.

As the oxygen and sulfide ions met and magma-heated water cooled down, gypsum crystals started to grow. Slowly, over the period of approximately 500,000 years formed crystals of incredible size.

Their creation was a lucky coincidence of many factors and one factor is – stable, uniform conditions with the same flow of water, the same pressure and temperature (around 54 °C) over these 500,000 years.

Already in 1910 miners hit an unusual cavern in Naica Mines – this cave was filled with enormous, up to 1 meter long, transparent selenite crystals. This cavern got a name – Cave of Swords (“Cueva de las Espadas”).

Eloy and Javier Delgado discovered the Cave of Crystals in April 2000 while excavating a new tunnel. Both miners nearly died while walking through the discovered wonder. This discovery became a worldwide sensation.

However, its discovery was pure luck – this new tunnel is located quite far from the main body of ore.

Cave of the Crystals is located 290 meters below the land surface.

The cave is shaped like a horseshoe, approximately 10 by 27 m large.

The most peculiar feature is the giant crystals of selenite (gypsum). The largest of these crystals is 12 m long, has a diameter of 4 m and its estimated weight is 55 tons. It is one of the largest known crystals in the world.

The floor of the cave is almost completely covered with these giant crystals but even more amazing are the selenite giants which protrude from the walls and ceiling and often reach the opposite side of the cavern.

These giant, translucent crystals have kept their morphological perfectness.

The cave is protected with a special door in order to minimize the impact of temperature fluctuations on the crystals. Other parts of Naica Mines are ventilated to bring down the temperature to a bearable 35 °C.

The temperature in the cave might reach 58 °C but for the most part of the time, it is 45 – 50 °C. Even more dangerous is the combination of the temperature and the high levels of humidity reaching 99%.

The human body will not survive in such conditions. There are no guarantees about the safe “working” of the heart and brain, hot water condenses in the lungs and interferes with free breathing, burning the eyes.

If a person loses consciousness in a cave, it is very difficult for others to rescue him. Others are exposed to the same dangerous conditions. Even 10 minutes in the cave will cause irreparable harm to health.

For this purpose, special protective equipment has been developed, and medics closely monitor the health of the cave researchers. The time spent inside these caves is strictly taken into account and very limited.

In Naica Mines have discovered 5 caverns with amazing crystals:

• Cave of the Swords (Cueva de las Espadas”)
• Cave of the Crystals (“Cueva de los Cristales”)
• Queen’s Eye Cavern (“Cueva del Ojo de la Reina”)
• Candles Cave (“Cueva de las Velas”)
• Ice Palace (Palacio de Hielo”)

The Cave of Swords was the first cave discovered. Experts suggest that the crystals in this cave are smaller because this cave is closer to the land surface and the heated water cools faster than in the Cave of Crystals.

The Cave of the Crystals was discovered in April 2000. In 2000, the Delgado brothers also discovered the Queen’s Eye cave at a depth of 300 meters. This is a cavity 8 m wide, lined with giant translucent selenite crystals.

In the same year, Candles Cave with absolutely unique crystals. In 2009, the Ice Palace was discovered at a depth of 150 m. It is not flooded, with smaller crystals, but impressive in shape – incredibly thin needles.

Maybe one day new caves will appear. There is also a possibility that the entrances to further caves are hidden behind the crystals in the Cave of Crystals, but exploring them will require significant damage to the cave.

The natural groundwater level in this place is at a depth of 110 meters. Thus, to maintain activities at the depth of 850 m mining company has to pump the water away. Each minute they are pumped away 55,000 liters.

This water irrigates the desert around Naica town. Thanks to this, agricultural land has developed here over the past decades. One day mining operations will end and groundwater pumps will be switched out.

And that day, the Cave of the Crystals will be filled with hot water again.

Since there is no water in the cave, the crystals quickly deteriorate. Their transparency decreases, cracks form and the crystals become brittle. Researchers find more and more pieces of broken crystals on the cave floor.

When water will be back in the cave, the formation of crystals will start again.