Hello friends, this week’s passion blog post is about the Giant Crystal Cave in Chihuahua, Mexico! The cave is 300 meters (or 980 feet) deep and 27 meters (or 89 feet) long. The crystals are made of hydrated limestone, or for those chemistry buffs out there, gypsum calcium sulfate (gypsum CaSO4·2 H2O).
The cave lies right above an ancient fault that is above an underground magma chamber. The magma heats the ground water, which is saturated with sulfide ions (more info for the chem nerds). When the cool oxygenated surface water combine with the heated ground water they do not mix due to their differing densities; the oxygen diffuses into the heated water and oxidizes the sulfide ions into sulfate ions. Then, the hydrated sulfate gypsum crystallizes at an extremely slow rate of over 500,000 years, which causes the accumulation that forms monstrous sized crystals.
The cave was almost discovered by miners in 1910 beneath the Naica mine workings. The miners found the Cave of Swords, which is a much smaller (but not necessarily less magnificent) crystal cave that is located above the Giant Crystal Cave. Scientists speculate that at this level of the caves, the temperature is much lower, which stunts the growth of crystals in the Cave of Swords. However, the Giant Crystal Cave was discovered in 2000 by miners excavating a new tunnel through the Naica fault, which they thought would flood the mine. The caves are only accessible today because the Industrias Peñoles mining company created pumps that go through the cave and drain the water out of the cave. If the pumps stopped, then the caves would be submerged in water once again. Unfortunately, the crystals deteriorate in air because there is no water to facilitate the chemical reaction needed to produce more crystals. That being said, the Naica Project, a group of scientists that research the caves, are attempting to visually document the crystals before they disappear.
A team of scientists led by Paolo Forti, cave mineral specialist and crystallographer (there’s a job title you probably never knew existed) from Italy’s University of Bologna, explored the cave in detail in 2006. In order to withstand the extreme temperatures and humidity, they team created their own refrigerated suits and cold breathing systems. They used special caving overalls fitted with a bed of refrigerating tubes placed all over the body. The researchers carried a backpack filled with ice water that flowed through the tubes to cool the body sufficiently for about half an hour at a time. In addition to mineral research, biogeochemical (another scientific field unheard of before this post), microbial, palynological (study of pollen), and hydrogeological research have been performed in the caves to gain a better understanding of its ecology.
If you want to explore the cave and see the crystals for yourself, there are some safety precautions to be aware of. The cave is about 136 degrees Fahrenheit with 90 to 99 percent humidity. Because of these extreme conditions, very few people have ever explored the cave. Without proper protection the average person can endure about ten minutes of exposure at a time.
Although not my forte, I learned so much from your chemistry insight regarding the caves. I’m someone that would read this and appreciate it’s beauty, without not understanding the movements and reactions that are behind the scene. I think it’s so important to gain scientific understand about our world, however there comes a line where we need to let it be and appreciate it for what we know. I think this is a perfect example of this line. If scientists have to make specific suits in order to explore these caves for limited amounts of time, odds are, they shouldn’t be there. If exploration continues, in a century, these caves will be nonexistent, bringing no beauty to our world.
This was a great read. However, It is unfortunate that scientist have to remove the water and initiate the collapse of these natural edifices. I do understand the importance they are for scientific study, but the cost at what it is to future generations (that is if you place much emphasis on these salt crystals) to cause the degradation of these natural obelisks is a bit much, but hey it must be right if it is in the name of science.
I particularly liked how you involved the brief commentary on the jargon for the molecular composition of these structures. This was a great read.
This was such a cool article to read. Thanks for dropping those chemistry facts for your favorite chem major. I never heard of this site, but that makes sense since it is only recently discovered. You brought up an interesting fact that should be discussed. Our human intervention is ruining this natural wonder, and we should think about if allowing it to degrade for our personal benefit is smart. Other natural wonders are highly regulated to ensure it longevity, sadly this sounds like a rose that will eventually wither away.