Deep beneath the earth in Chihuahua, Mexico, grows a real world fortress of solitude. In 1910 and the Nica mine in Mexico, the Pinolis mining company discovered what came to be known as the Cave of Swords. It was an 80 meter long hallway with beautiful gypsum crystals growing up to 2 meters in length. Unfortunately, the cave was opened up for exploration and later tourism, which destroyed many of the crystals. 90 years later, two miners working for the same company stumbled on another cave, except this one was much, much bigger. Nica sits on an ancient fault line above a magma chamber. This heated the groundwater and filled it with sulfide ions. So when this hot sulfide brew met with the cool oxygenated water in the cave, they didn't mix exactly, they kind of sat on top of each other, but the oxygen began to diffuse into this rich sulfide soup and slowly, an infinitesimal pace, these crystals began to form. They have been growing for half a million years. Today, the largest crystal in the cave is 12 meters in length, 4 meters in diameter, and 55 tons. It is 20 times bigger than any previously known crystal. Amazingly, there's no limit to how big these crystals can get. Given enough time, they will grow ever larger. These are fortress of solitude crystals. They are Superman crystals. One big difference between the fortress of solitude and the cave of crystals is the temperature. The cave of crystals is blisteringly hot. It is 50 degrees Celsius or 122 Fahrenheit, and the humidity level is a constant 90 percent. Even wearing special cooling suits filled with ice and water, researchers were only able to spend about 40 minutes down there. These crystals grew underwater. It's only in the last 20 years this mining company has pumped out all of the groundwater so they can extract various precious ores from the area. But as soon as it doesn't make economic sense for this mining company, the crystals will be re-submerged, returned to their underwater existence. And this is probably for the best. Because, well, it's incredible we get the chance to study them now. That's their natural environment. It's where they grew. It's where they can keep growing. And I think considering how beautiful, but also how fragile these are, just knowing that their under your feet growing ever larger is more than enough. Subscribe here and watch more videos. Here, this is Injipsum, this is self. The NICAPROCHT is doing a ton of amazing science around this, including looking at ancient life forms in these crystals and trying to find their closest relative. I've included a link down below if you're interested in learning more about that.