Three hundred metres below the earths surface in a hot humid cavern, lies crystals as large as telephone poles, undisturbed for thousands of years.
In Naica, Mexico exists a cave that should be deemed a wonder of the world. Discovered by two miners in 2000 on a routine check, the cave bursts with crystals of gypsum, whose size is unrivalled. And yet, it wasn’t until 2007 that scientist realised the importance of this discovery!
The crystals are a form of gypsum called selenite, growing from the walls of the limestone cave. The largest crystal pillars are 11 metres long and 55 tonnes, making them as high as telephone poles and 100 times as heavy. Gyspum rosettes continuously line the cave floor and walls; the gypsum rose I own is a mere 2 cm.
The crystal edges are sharp enough to cut bare skin, but so soft they can be scratched with a fingernail. Simply walking on the crystals is a danger as they are slippery and prone to break. Although they may look like icicles, these crystal are scorching hot to touch.
Why? – Being situated 300 m under the earth, places the air temperature at 40°C. Within the cave itself, temperatures spike at 45°C.
Explorers and scientist have a hard time viewing this natural wonder. To an extent their lives are on the line. This is one of the hottest places on earth humans have tried to survive! The temperature means organs can fail and cells can die, and 100% humidity means sweat cannot evaporate and thermoregulation is impossible. Ice suits and respirators are needed for these risk-taking individuals to even survive in the cave for half an hour. Breathing the hot air itself can scorch throat. The Sahara temperature meets the Amazon humidity all in one cavern the size of a football field and the height of a two story building.
Scientist however have braved this incredible and bizarre conditions, risking their lives for their work and passion. It is thanks to their efforts, we understand how this cave came to exist.
Gypsum crystals this big need two crucial ingredients to grow: submergence in water, and heat in excess of 50°C. Since gypsum takes a long time to grow, the cave must have been stable and under water for a prolonged period. This is uncommon in nature, as demonstrated by the second largest gypsum crystals being only 2 m in length. The water, heated to 58°C by an underlying magma body, was super-saturated in gypsum. The gypsum clung to the cave walls and floor, and began growing as microscopic crystal, and then just kept growing and growing.
Prof. Stein-Erik Lauritzen collected a core sample from a large crystal for U-Th dating. His team determined an age of an astounding 500,000 years! This means 1.5mm of increase per thousand years, for half a million years!
So why did it take so long to find? Two reasons really: depth and submergence in scalding water. The cave is only in temporary existence. It is only due to the lead and silver mine pumping away the water in the year 2000 that this spectacle was uncovered. If the mine becomes unviable, then the pumps will be switched off, the cavern will flood, and all will be as it has been for the past 500,000 years. Since it’s exposure though, the crystals have been eroding and collapsing. As the temperature in the cavern drops year by year, so does the crystal’s stability. So do we flood it to preserve the crystals, and loose them forever to human eyes? Or do we view and explore until it is no more?
Either way, we are still left with a strong impression of if something can be hidden from us for so long, then what other wonders is the earth and ocean concealing from our eyes?
My 6-year old cousin loved watching a youtube video about this so much, she drew me a picture! That’s me in the cave by the way! And yes she even included a gypsum rose down the bottom, and no I didn’t force her to draw this, she did it of her own free will 🙂