Giant Crystal Columns Crowd a Cave in Mexico

giant crystal cave
The interior of the Cave of the Crystals (La Cueva de los Cristales) in Naica, Mexico. It was discovered during operations at a nearby silver mine. The crystals run to several meters in length and people could only explore the cave for short periods of time.

By Alexander Van Driessche [CC BY 3.0 (https://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons 

Imagine an otherworldly realm where clear, shimmering crystalline pillars glow in a hot and humid darkness. Cueva de los Cristales, or Cave of the Crystals, is a geologist's dream. Located hundreds of meters underground in Naica, Mexico, the cave resembles nothing so much as an alien cathedral, with a roof propped up by huge selenite crystals.

How the Crystal Caves Were Discovered

Located right next to a mine complex, the cave was discovered in the year 2000 by a pair of miners named Eloy and Javier Delgado. It lies beneath another smaller crystal cave that was discovered in 1910. Other, similar caves are nearby: the Ice Palace, Cave of Swords, Queen's Eye, and Candles Cave. They, too, contain fantastic-looking crystals and mineral deposits, cooked up by a seeming magical alchemy of heat, chemistry, and geology.

Like La Cueva, these caves were discovered by local miners. The surrounding region has a very high water table, and the owners of the nearby Industrias Peñoles Naica mine had to pump out as much water as possible in order to access the mine's silver and other minerals. ​Pumping the water from the mine had the effect of removing water from the nearby crystalline caves as well, paving the way for their discovery and scientific exploration.

Cave Life Defies Inhospitable, Otherworldly Conditions

giant crystal cave
Astrobiologist Dr. Penny Boston and a colleague study and sample a selenite column in La Cueva de los Cristales in a search for embedded microbes. Like all visitors to the cave, they had to be dressed in special protective gear and take precautions to avoid contaminating their samples with "outside" life forms. European Space Agency 

This eerily beautiful crystalline cave houses a deadly environment, where the temperature never drops below 58 degrees Celsius (136 F), and the humidity hovers around 99 percent. Even dressed in protective gear, humans can withstand the dangerous conditions for only about ten minutes at a time. As a result, tourism is forbidden; only scientists have accessed the cave, with miners acting as guides.

The selenite needles require a warm, wet environment to survive, and scientists had to move quickly to study the cave while it was accessible. Microbiologists, working under stringent conditions to prevent contamination, bored into the columns to get samples of life forms that might exist in the fluids trapped inside the crystals. 

In early 2017, researchers reported finding dormant microbes inside the crystals. They had probably been trapped inside the crystals at least 10,000 years ago and possibly as long as 50,000 years ago. Some bacteria living in the cave do not match any other known life forms on the planet. 

Although the microbes were dormant when the scientists found them, the researchers were able to reanimate them in the lab to get more information about what they are and conditions in the cave when they were trapped. These "bugs" are referred to as "extremophiles" because they can exist and survive very extreme conditions of heat, humidity, and chemistry. 

Today, with the cessation of mining operations, the pumping has stopped. Reflooding has preserved the crystals for now, but it has also introduced new organisms into the chamber that are foreign to the environment.

How the Crystals Formed

giant crystal cave Mexico
Selenite crystals found in the Naica mine formed over hundreds of thousands of years. Assignment: Houston One, Creative Commons Attribution, Share-alike 2.5.   

The mine and cave are above a giant magma chamber that stretches for several miles below the surface. This underground "pool" of lava sends heat (and occasional lava flows) upwards to the surface. The overlying layers of rock are rich in sulfur and other minerals common to volcanic deposits. The groundwater in the region is also rich in these minerals, as well as in sulfur ions (sulfide ions). 

Over time, groundwater and fresh water (from rain, for example) slowly began to mix. Oxygen from the fresh water eventually made its way into the groundwater, where it began forming sulfates. The mineral gypsum, part of the sulfate family, gradually crystallized into selenite columns that grew slowly in the wet, hot, humid environment of the cave.

Geologists estimate that the columns in Cueva de los Cristales may have taken half a million years to reach their current lengths of several meters. 

Similar Alien Environments

Europa and ocean
Europa may have a hidden ocean beneath its icy crust. Although that subsurface environment may be "extreme" just as the Naica cave is, it's possible that it, too, could harbor life. NASA

La Cueva de los Cristales is a good example of what some refer to as an "alien environment" on Earth. Scientists know that places exist elsewhere in the solar system where extremes of temperature, chemistry, and humidity might not seem hospitable to life. Yet, as Cave of the Crystals demonstrates, microbes can survive extreme conditions, such as in desert regions or deep underwater, or even encased in rocks and minerals.

If these so-called "extremophiles" can form and thrive on our planet in challenging conditions, then  chances are good that microbes can exist on other worlds in similar conditions. These could include Mars or Europa, or perhaps even the very alien environments of the clouds of Venus or Jupiter. 

While the reflooded cave is now off limits for study, future exploration is not out of the question should it be pumped out again. However, future scientists will face a slightly different set of life forms. Those will be the ones that humans brought in as they entered the cave to explore its previously pristine environment. 

Cave of the Crystals Key Points

  • La Cueva de los Cristales contains the largest-ever seen selenite crystal columns in the world. It's adjacent to a mine in the Mexican state of Chihuahua. 
  • The combination of heat, water, and minerals helped these columns grow.
  • Biologists found ancient, dormant organisms embedded inside the crystals that resemble no other known life on earth.

Sources

  • Mexico.mx. “Naica Cave, Mexico's Underground Crystal Palace.” Mexico.mx, 15 Sept. 2017, www.mexico.mx/en/articles/naica-cave-mexico-undergroudn-crystals.
  • “Penelope Boston: Lessons from Life in a Cave.” Genetically Engineered Crops at the National Academy of Sciences, nas-sites.org/bioinspired/featured-scientists/penelope-boston-lessons-from-life-in-a-cave/.
  • “The World's Largest Crystals Are Growing in a Cave in Mexico.” Travel Leisure, www.travelandleisure.com/trip-ideas/nature-travel/cave-mexico-largest-collection-crystals.
  • “Weird Life Found Trapped in Giant Underground Crystals.” National Geographic, National Geographic Society, 17 Feb. 2017, news.nationalgeographic.com/2017/02/crystal-caves-mine-microbes-mexico-boston-aaas-aliens-science/.