Cave of Crystals

NaicaMexico

26 Feb

Deep in the earth could be whole ecosystems without our knowledge

The earth’s crust seems to be quite the enigma, and certainly when you find a cave chook full of massive crystals.

The discovery

Over in Mexico, about 300 metres below the mining town of Naica is a massive cave full of crystals that looks like it’s straight out of a science fiction show.

The Cueva de los Cristales, or Cave of Crystals for those who aren’t up on their Spanish, is a cave full of humungous selenite crystals. But it’s not the only one of its kind.

Throughout the early 19th century, a lead and silver mine started operation, though it wasn’t until 1910 that the Peñoles Mining Company stumbled across something fascinating. About 120 metres below the surface, a cave was found lined with decent sized selenite crystals, these ones only about 2.5 metres long. This mine was called the Cave of Swords by the local miners. And it wasn’t the only one to be found, similar crystal caves like the Ice Palace, Queen’s Eyes and Candle Cave have been found as well.

Now the whole area around the Naica mines have a very high water table, so the mining owners had to pump out as much water as possible so that they could access that sweet sweet silver. And it’s this very act of pumping out the water that has led to a world of discovery.

Back in 1927, William Foshag from the US National Museum was granted access to the Naica caves, not the Cave of Crystals because that one hadn’t been discovered yet, but the smaller crystal caves. Here’s what he described in American Mineralogist:

The gypsum crystals have grown to an enormous size. Many of them are four and five feet long and a few probably reach six feet. They grow from the floor of the cave … These large crystals are coloured a light gray by included mud but are often capped with a clear white termination.

What an amazing description, it must have certainly been a sight to behold. But as we know it would be nothing compared to the Cave of Crystals.

Back in 2000, two brothers, miners themselves, accidentally stumbled upon our cave. A bit underneath the previously discovered Cave of Swords is a chamber stuffed full of massive crystals. The chamber itself is a rough horseshoe shape, about 10 metres by 30, and is stiflingly hot sitting at around 50 degrees Celsius, but it’s the almost 100% humidity that will get you. We’ll go into this a bit later on, but humidity that high can be extremely dangerous. But what’s absolutely fascinating is the blocks of crystals that look as if they’re growing out of the floor and holding the roof up. They certainly are the largest gypsum crystals known to have grown anywhere, and it’s even been said that their lustrous colour has been compared to moonlight.

Juan Manuel Garcia-Ruiz a geologist from the University of Granada said this about his experience of the Cave of Crystals:

There is no other place on the planet where the mineral world reveals itself in such beauty.

Fortunately for the Cave of Crystals, it has remained intact the last 20ish years. Unfortunately for the Cave of Swords, the 1910s were a time of not exactly great practices and its crystals were pillaged, with collectors taking the larger and more beautiful of the crystals.

So what is the size of the massive crystals then. Well the largest are up to 14 metres long and 2 metres thick. So pretty bloody big. Although a majority of them are about 10 metres long, still nothing to turn your nose up at. When pictures of the cave first went public, the world was astonished. How could such monolithic crystals be formed? That’s actually something we’ll go into a bit later on, first let’s find out a bit more about the scientist’s experiences when visiting the cave.

Carlos Lazcano, a speleologist and historian, was actually the first scientist to go inside the Cave of Crystals. He was visiting a couple of his geology students, who were doing some work in the mines in Chihuahua when he ended up talking to the foreman of the Naica mine, who told him that while digging a new side tunnel, they’d broken into a new cave and offered to show Lazcano around. Which of course Lazcano was all for. He’d known of and visited the Cave of Swords so was really excited to see what this new cave held. This is what he had to say about his experience of stepping inside:

It was a surprise with capital letters! I was amazed not only at the size of the crystals but also at the aggressiveness of the environment surrounding them.

That environment he’s talking about is the fact that it was 50 degrees and an incredibly unpleasant 100% on the humidity scale.

Dr Penelope Boston, a famed Naica scientist and researcher had an almost transcendent experience the first time she entered the cave:

The beauty of the environment was completely entrancing. It was a precious gift to be able to experience that amazing place … The first time I entered … tears came to my eyes and I put my arms around some of the giant crystals and felt that I was actually a part of the cave system. That day, when I got out, I wrote a poem about it.

Sounds like an incredibly moving place. So moving that Lazcano was eager to get a research project on studying the crystals started.

When Claude Chabert, one of France’s most famous cavers stopped by for a visit they got straight into it:

In April or May of 2000, we got full authorisation to explore the cave, so the two of us were the first speleologists to try to study it. Both of us were excited by those bizarre giant crystals, but at the same time, we just couldn’t believe how hostile the cave was. We couldn’t stay in it for more than five minutes at a go! If we tried to make it to six minutes, we felt like we were dying!

Sounds like exploring the cave early on was quite the dangerous excursion. But Lazcano had the idea to contact his friends over at La Venta Association, a company based out of Italy that organises scientific underground expeditions. These guys had explored volcanic caves before where the temperature was sitting around 80 degrees Celsius, so much higher than our Cave of Crystals, surely they’d be able to help Lazcano and Chabert in how to explore the cave in a safe manner.

I couldn’t believe how fast they showed up here … and that’s how Project Naica got started!

How to create massive crystals

So the Naica Project consisted of 12 working trips to head down and explore and study the cave. Everything was organised by the Italian La Venta Exploring Team, who are pretty bloody experienced having carried out projects in caves as far as Myanmar and Patagonia. So there’s no doubt they know their stuff.

Dr Penelope Boston, who – side note – currently works with NASA and is helping to design exploration techniques on Mars, has said that studying the crystals in the cave was no walk in the park.

[The caves are] like being in a sauna for a long time while climbing around with difficult footing and trying to do delicate scientific operations all at the same time. It was extremely challenging.

But Dr Boston wasn’t about to let these challenges get in the way of scientific inquiry. Her purpose for being in the Naica mines was to look for signs of life hiding among the crystals. And she and her team were actually able to grow microbial cultures from fluid they had managed to extract from the centre of the giant crystals. See sometimes when the crystals were growing pockets of liquid would be trapped within the crystal and it was this liquid that contained unique bacteria that Dr Boston was able to reanimate in her lab.

From these cultures a remarkable discovery was made. In 2017, Dr Boston and her team announced that the bacteria they had grown from the dormant microbes pulled from inside the crystals were genetically distinct from anything else known on Earth. You know what that means? Teeny tiny aliens! Not really, but Dr Boston reckons that they’ve been trapped inside the crystals for anywhere between 10 000 and 50 000 years, so teeny tiny really old aliens. No they’re not really aliens, the thought is that because they were trapped in a dark liquid environment they just didn’t evolve like the rest of bacteria on the surface of the Earth and so literally went a different way, making them genetically distinct from everything else we know.

But how did we get to this spot in the first place? With giant crystals and super old micro-organisms hanging out? Well, we’ll have to go all the back to 26 million years ago when some stock standard volcanic activity started moving land around and created the Naica mountains, filling the inside of the mountain with anhydrite, which is a form of gypsum, what we know the crystals to be made from.

Now at any temperature higher than 58 degrees Celsius, anhydrite is a pretty stable substance, just chilling out, not doing much. But any lower than 58 degrees and it turns into gypsum. Initially the lava from the volcano kept the anhydrite sitting in the mountain above the nice and toasty 58 degrees. But as the planet started to cool and life started to form, so too did the magma underneath the mountain.

So as the mountain cooled, the temperature got lower and lower until it was no longer 58 degrees and the anhydrite started to become unstable and dissolve, making the pools of water that had appeared in cavities in the cave rich with sulphate and calcium. And it’s this unique combination that has allowed the huge selenite gypsum crystals to form. And there really is no limit to how big they can grow, if left undisturbed they will just keep growing and growing and growing, as long as the environment stays optimal for growth, that’s what the crystals will do.

But so how did the crystals in the Cave of Crystals become so much larger than the crystals found in the other caves. Well the geologist, Juan Manuel Garcia-Ruiz says that for them to have grown to such a gigantic size, the temperature in the cave had to have sat just below 58 degrees for hundreds of thousands of years. While in the caves a bit closer to surface, like the Cave of Swords, the temperature would have dropped lower than 58 degrees a lot quicker. Here’s what he says:

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

So the deeper the cave is, the slower the temperature drops, allowing more time for the crystals to grow at the perfect temperature, and the shallower the cave is, the faster the temperature drops, meaning there’s not much time for the crystals to grow leading to smaller crystals.

But as we know from those ‘Make your own crystals at home’ kits, it’s not just the temperature that matters, it’s also how wet the environment is as well. We know that the Cave of Crystals was previously submerged in nice warm water, because the mining company had to pump water out in order to gain access to it. So for now the growth of the crystals has been paused, because there’s not enough water.

Which means that microbiologists studying the crystals are trying to take advantage of the lack of water while they can.

But because the place is still quite uncomfortably hot, that means that the magma directly beneath the cave is still actively flowing, creating the sauna-like conditions in the cave that the scientists have to confront every time they enter.

I imagine being starved of the water that literally gave you life isn’t exactly fun for the crystals either, in fact it could actually be harmful, since the buoyancy of the water is no longer helping to hold the crystals in place. But something that’s really quite exciting for scientists to ponder is the possibility that there could be caves in the Naica mines with even bigger crystals because they would be in a cave that’s even deeper in the ground, meaning they would have been at the optimal temperature for growing for that little bit longer.

Preserving the crystals

Something the scientists take rather seriously is the preservation of these crystals. Because there’s no more water surrounding the crystals, only an extremely humid environment, the scientists and researchers allowed into the cave to study the crystals have found that the moisture in the gypsum surface can be dehydrated, which could lead to weakening of the crystals structure and eventual cracking. And this means that the crystals are at serious risk of breaking. So perhaps some tough decisions need to be made.

A lot of times in the art world, priceless and irreplaceable objects are so delicate that it only makes sense to not put them out on display at all, as any change in light or humidity or bacteria can be most harmful. That’s why you’ll see some works of art displayed in dim rooms with protective casing surrounding them. There’s even the example of the Lascaux Cave in France, where some of the coolest rock paintings have been found. The decision was actually made to close the cave. The light, air and even breath of tourists coming to see the art were just wreaking havoc on the walls of the cave. Imagine lichens, moulds and crystals starting to grow. Not exactly the best way to keep this remarkable piece of human history safe. So the tough decision was made to close access to the cave. Now as a tourist you can’t visit the actual cave, but you can pop in next door and check out an exact replica. And if you didn’t know any better, would you really know the difference?

But the argument has been made that something similar could possibly happen with the Cave of Crystals. Not withstanding the horrid conditions, perhaps it would make sense to create an exact replica for tourists to stop by and have a look or even a virtual hologram exhibition or virtual reality display, the ideas really are endless when technology gets involved. Especially since a new study has found that exposure to different atmospheric conditions, such as those we enjoy on the surface, could be altering and dissolving the mineral surface of the crystals.

So what are the other options we have available to us to protect this delicate environment?

Well the suggestion has been put forward to resubmerge the crystals, possibly allowing them to continue growing. The current temperature conditions are still within the optimal range for growth, and water is still wanting to enter the cave, hence the continued pumping by the mining company. So even though draining the cave has allowed scientists to peak into the world of the giant crystals, despite the incredibly harsh environment, is it time to allow the water back in?

Of course doing this would make access to the cave impossible. But as we know the removal of the water has its own risks. The largest beams in the cave are estimated to weigh around 40 to 50 tons, and without the buoyant support of the water, there is a serious possibility of them cracking under their own weight.

Not to mention that gypsum is actually quite a soft material, and having scientists walking through the cave hasn’t done it any good. There are actually blackened paths on the crystals on the cave floor where the scientists have trodden on them as they’ve gone about their expeditions.

But like most things in life, it all really depends on the resources that the state or national authorities are willing to set aside for this incredible place.

Fancy a visit?

We already know what Dr Penelope Boston thinks about the place:

It is tear inducingly beautiful down there. I wrote several poems about it actually.

Great, so when can we go visit and experience this beauty for ourselves? Well, unfortunately, no tourists are allowed to visit the Cave of Crystals. And it’s for a pretty important reason. The hot and extremely humid conditions actually make the cave a particularly dangerous and hazardous place to visit, even the scientists that are given approval to go need to get a special permit. Even then with all the permits, some scientists aren’t even allowed to enter the cave, they’re only allowed to look in through the window at the cave entrance.

The real dangerous, possibly fatal, thing is the humidity. With humidity, and the temperature of the air itself, being so high, it means that when you breath in the air, the surface of your lungs is actually the coolest surface that air has come into contact with. And because there’s so much moisture in the air itself, it starts to create condensation. But condensation inside your lungs isn’t the best, and you can literally drown. Not from the water in the cave, because that’s been pumped out, but from the condensation building up inside your lungs. That’s why the scientists are only allowed to be in the cave for no more than 10 minutes, and even then in specially designed suits. The possibility of condensation getting into their lungs is just too great.

The suit the scientists have to wear is a funny one. It’s basically a suit of chainmail, but filled with ice cubes to keep them cool. Then a breathing mask allows them to breath cool, dry air to keep their lungs water free. They can take the mask off, but only for a short time.

The real danger in the cave is tripping on a crystal as they move around and falling. If they were to hurt themselves, it would be a mighty hassle to rescue someone. The rescuers would need the special suits, and they would need to carry the injured person out of the cave, without tripping over themselves. So careful footing is a must.

Now while you can’t access the cave, you can still visit the mining town of Naica. The culture there is fascinating and if you find yourself there in early December, you might just stumble upon the celebrations for International Mining Day.

Now back when the cave was first discovered and everyone wanted to know more about this fascinating cave, Gonzalo Infante, a Mexican cinematographer, had the bright idea to make a documentary about the cave to show this amazing natural wonder to the world. But thanks to the ridiculously tough conditions inside the cave, every single camera that Infante brought in failed. Eventually he was forced to bring in a robot-mounted Nikon camera that would take photos of the place. As the camera was rotated by the robot mount, a new still photo would be taken. And it was in this fashion that Infante shot his movie, one frame at a time.

To get 10 seconds of movie, the robot had to shoot stills for six hours. Many times, we just left the thing on, and it would run all night long.

The film actually turned out pretty well. National Geographic even used Infante’s footage in a clip.

Fortunately for those pondering the best way the go about protecting the Cave of Crystals, a couple of years ago the decision was made for them when the Naica miners accidentally broke into an aquifer. Unable to stop this new flow of water, the mine, and therefore the cave, flooded. Meaning that the caves are now filled with water once more, and are no longer accessible.

While this reflooding is preserving the crystals for whatever the future holds, it’s those scientists that may be able to re-access the cave in the future who have an exciting experience ahead of them. Because the new water entering the cave will be introducing new organisms that are foreign to what the cave has previously housed, the possibility for there to be different micro bacteria is pretty likely. So something to look forward to.

If you want to get a feel for the cave, you can learn all about what can form in underground caverns over at the Mineralogy Museum of Mexico. It’s also there that you can check out the ongoing conservation efforts for the other caves closer to the surface. And if you ever find yourself in New York City, head on over to the Astro Gallery, the world’s largest gallery of gems, minerals and fossils. They reportedly have 80 cm long selenite crystal from the Naica caves on display. An excellent way to see a fascinating crystal without the risk of drowning in super humid air.

And while tourist visits are well out of the question, there is the possibility that another cave with massive crystals could be found, or even another entrance into the Cave of Crystals. So who knows, there could be some fascinating updates in the future.