A geological pilgrimage to the Cave of Crystals, Chihuahua, Mexico
This month’s Accretionary Wedge, hosted by life as a geologist, asks bloggers to discuss a geologically cool place that they would love to go or have been to, a sort of ‘geological pilgrimage.’ This place should be:
“geologically unique, relatively remote, and requires some difficulty to get to. If you have already done your geological pilgrimage, please share with us your experience. If you are still planning your pilgrimage, then let us know where your sacred geological spot is and why.”
Almost exactly three years ago (in April 2009), I had the rare opportunity to go visit the ‘Cueva de los Cristales‘ in a remote part of the state of Chihuahua, Mexico. It was a once in a lifetime opportunity and one that I will always remember, for the fascinating geology, the trip to get there, and the temperature inside the cave, which was an experience in itself. Let me preface this whole story by saying that I liberally use facts from the fascinating paper published in Geology on this area by Garcia-Ruiz et al in 2007.
The cave was discovered in the Naica Mine, which produces lead, silver, and zinc from hydrothermal veins in a Cretaceous limestone sequence. The hydothermal activity is associated with Tertiary volcanic activity, and there is still an active magma chambers about 5 km away from the mine. Hence, the mine, and cave, is very warm (more on that later). The cave was discovered in 2000 during mine exploration, and had to be drained to be accessed. Once the miners went inside, they realized that this was something special – many caves with large crystals had been found due to the unique geological conditions in the mine, but nothing even close to this. Single crystals of selenite (a colorless, crystalline form of gypsum) up to 1.5 m in diameter and ~15 m in length littered the cave, growing from floor to ceiling, leading the miners to call them vigas, or ‘beams’. National Geographic came in, and using advanced photography, captured some great images, including the one below:
The article on Nat Geo is worth a read, as it discusses the crystals, and the hardships of the explorers. Needless to say, we didn’t take as high quality photos as them, but we enjoyed it nonetheless. Now before you say you want to go too, the mine is private and does not offer tours of the mine or the cave. A friend of one of the people in our group had some connections, and we were just lucky to get to go.
Of course we jumped at the chance, and on only 3 days notice, 6 of us flew into Chihuahua city and met the rest of our group. We then took a few suburbans on a 2 hour drive through farmland and orchards and then up into the Naica mountains where the mine is. Upon arriving, we had an orientation and were issued safety gear. We then jumped into a big van and headed down the main mineshaft. The cave is located about 300 m vertically under the ground, but it is a 20 minute drive down due to the angle of the mineshaft. It got hotter as we went down, and was about 95 degrees F and humid in the mineshaft outside the cave. Our guide then opened a steel door, and we walked into the anteroom of the cave. It was even hotter in here, maybe 110 degrees F. We walked upslope to the cave entrance, which is only about 2 m across, and is sealed by a glass door.
When the door was opened and I stepped into the cave, it was like hitting a brick wall. It was so hot and humid that you immediately start sweating, and it is hard to breathe. I didn’t have a thermometer, but our guide said the temperature was about 130 degrees F and 99% humidity, and Nat Geo confirms that. However, I soon forgot about the heat and tried to pick my jaw up off the floor when I saw the crystals. They are so large and stunningly translucent that it seems impossible that they are real, and natural. So here it is, proof that I went to the Cueva de los Cristales in Naica, Mexico:
That crap-eating grin is me enjoying the crystals, before I started sweating. Here is what another of our group (who just happens to be my dad) looks like after being in the cave for a few minutes:
Sweating profusely, but in wonderment of the crystals. We were only allowed to stay in the cave for about 15 minutes, then we had to take a 30 minute break and drink water before going in for another round. After two rounds in the cave walking around and looking at the crystals, this is what our group looked like:
I am in the lower right corner, drenched in sweat, but still have that same grin on my face. It was an unreal experience, and one that I have a hard time relating on paper. It was simply one of the coolest things I have ever done, or ever will do.
When I got home I found the Geology paper mentioned above, and learned the rarity of the formation. According to Garcia-Ruiz et al (2007), it seems that these crystals grew in briny waters of ~ 54 degrees C. These geochemical conditions had to remain constant for a very long period of time in order to grow such large crystals without nucleating lots of small crystals – no temperature fluctuations, no large earthquakes, no changes in salinity. They estimate that the growth of the crystals took 10^6 years – yes, that’s millions of years!
So this truly is probably the only place on earth where such a geological wonderland exists. I encourage you to read the Nat Geo article and watch the associated videos, and also to read the Geology paper – it is fascinating, and goes into much more detail about the local geology and the formation of the crystals.
That was my geological pilgrimmage – a once in a lifetime visit to a Cave of Crystals that only a few hundred people have ever been to, and when it is flooded after mining operations cease, I hope the crystals keep on growing…