The Giant Crystals of Naica, Mexico

Stephanie Spavento February 8, 2014

1,000 feet under the town of Naica, Mexico lays a cave filled with some of the largest crystal formations in the world. Originally discovered in 2001 by two miners looking for lead, the “Cueva de los Cristales” is terrifying and beautiful at once. With internal temperatures up to 140°F and over 90% humidity, it feels closer to 220°F to the daring people who venture past the mouth of the cave.

naica, mexico

Cuevas de los Cristales, Naica, Mexico (photo source:

Because of the extreme conditions, those who enter the cave must wear protective gear, and can only stay for about thirty minutes at a time. The heat and humidity, however, are exactly what allows the gigantic crystals to form. The selenite, or, commonly, gypsum, in the surrounding rock is dissolved into the naturally-heated underground water, creating a super-saturated solution. As it cools slowly over time, enormous crystal columns emerge. The massive crystal rods that are created here can measure over forty feet and weigh fifty-five tons.

Imagine wandering into a dark, hot, dank cave to find a room full of sparkling clear and white crystals, as tall and as massive as trees, jutting out from every surface. Given enough time, and under the right conditions, the crystals grow and grow and grow. It is estimated that it took hundreds of thousands of years for these colossal crystals to develop. Today, giant gypsum crystalline rods, as big as rafters, dwarf any visitors who come to witness the cave’s beauty for themselves.

In 1910, a similar, but smaller, cave was discovered. Called “Cueva de las Espadas,” or the Cave of Swords, it was tragically destroyed by overuse and tourism.  Juan Manuel Garcia-Ruiz, a geologist from Spain’s Instituto Andaluz de Las Ciencias de la Tierra, is trying to save “Cueva de los Cristales” from the same fate. He is campaigning to convince Mexican officials to claim the cave as a UNESCO World Heritage site because the probability that these specific conditions could be recreated anywhere else in the world is very low. “Cueva de los Cristales” is breathtaking to behold: walls of selenite crystals protrude out like the spines of a giant glass sea urchin. It is like walking around inside a massive geode.

Each room of the cave has its own unique crystal formations; some are as tiny as glistening snowflakes, and others are more massive than trees. Some rooms are covered, floor to ceiling, in small shimmering spines; while others can only house a couple substantial rods. The geological forces and time it took to create “Cueva de los Cristales” are palpable and astounding.