Naica’s crystal cave captivates chemists

Giant gypsum crystals reveal their secrets by Emma Hiolski

Deep below a mountain near Naica, Mexico, miners searching for fresh ore deposits in 2000 came across an unexpected and awesome sight. Massive, milky-white crystals towered around them, filling a horseshoe-shaped cave. Luminous beams of gypsum bigger than telephone poles, nearly 12 m long and 1 m wide, gleamed in the miners’ lights, jutting in all directions out of the brown limestone walls, floors, and ceiling.

The Cave of Crystals, as it became named, is nestled 290 m underground, topped by a mountain rich in lead, zinc, and silver. Since its discovery by the mining company Industrias Peñoles, the subterranean chamber has drawn researchers from around the world, enticing them with both rare beauty and scientific mystery.

Juan Manuel García-Ruiz, a crystallographer at the University of Granada, traveled all the way from Spain to see the crystals for himself. García-Ruiz had grown crystals in laboratory flasks since age 15, so walking among the Naica crystals was, for him, the moment of a lifetime. “When I entered the first time, after the first couple of minutes of stupor, I burst out laughing. I was euphoric,” he says.

In the years since the crystals’ discovery, researchers—including García-Ruiz—have braved the cave’s oppressively hot and humid conditions to answer questions about the crystals’ origin and growth. Now, almost two decades later, having answered many of these questions, scientists are pivoting toward learning how to protect and preserve the crystals for future generations—if the forces at work in the mine and the mountain permit it.

This project was blessed by the Dalai Lama.

One stone, in particular, is especially amazing. First discovered in Uruguay, South America, this 120 millionyear-old rock is the largest amethyst cave ever discovered in the world. It’s about 18 feet wide, large enough to sit in, and weighs 20 tons.

The owners of the Crystal Castle purchased it from an Uruguayan farmer as a celebration of the Crystal Castle’s 30th year. In order to experience it, you’ll want to book the Enchanted Cave Immersion, an hour-long guided experience for you and up to 3 of your friends to meditate in the belly of this geode.

The castle also has the tallest pair of bookmatched geodes in the world. The 18-foot tall smoky quartz geode was also purchased from the Uruguayan farmer. And in 2012, they added the only Kalachakra Stupa — a stupa (a moundlike structure containing relics used in Buddhism for a place of meditation) whose symbolism isn’t connected to the Buddha’s life but instead is used to protect against negative energies. It’s the rarest kind of stupa, and this project was blessed by the Dalai Lama.

When they first began their venture on their 12-acre property, Naren King, the castle’s “managing dreamer,” was scoffed at as one of the “offbeat hippies out of the back of Byron Bay.” He and his family have since watched the dream come to success. The Shambhala Gardens are world renowned and the castle is considered a significant tourist attraction.

43 The Giant Geode of Pulpí – Unlocking the Mystery of the Giant Crystals

This incredible natural space is the Geode of Pulpí,

the closest thing in real life to Superman‘s Fortress of Solitude: an amazing egg-shaped cavern where jagged shards of brilliant, clear crystal jut from the walls like teeth in a dragon‘s mouth.

The geode of Pulpí is an 11-meter hollow ovoid with crystal-paneled walls. It is like those familiar couplets of stone interiors covered with bright crystallites, but so large that several people can fit inside. The crystals, of up to two meters in size, are so transparent that they look like ice crystals. In this paper for Geology, Juan Manuel García-Ruiz and colleagues reveal the geological history that ended with the formation of the Pulpí geode.

As far as geodes go, Pulpí‘s is a giant – one of the largest known geodes in the world in fact.

In terms of cavernous chambers, though, it‘s actually tiny, but is large enough that multiple people can fit inside it at once, which isn‘t something you can say about most geode cavities.

Like the giant crystals of Naica in Mexico, the crystals of Pulpí are gypsum (calcium sulfate with two water molecules). García-Ruiz says, “To reveal their formation has been a very tough task because unlike in the case of Naica, where the hydrothermal system is still active, the large geode of Pulpí is a fossilized environment.”

The team performed a study of the geology and geochemistry of the abandoned mine where the geode was found, including a detailed mapping of the underground mining works, which has been used to allow the tourist visits in the mine.

They found that the crystals of Pulpi formed at around 20 °C, at a shallow depth where the temperature fluctuations of the climate are still perceptible. These temperature fluctuations, being below the maximum solubility of gypsum (40 °C), led to the dissolution and recrystallization amplifying a maturation process that is known as Ostwald maturation.

Says García-Ruiz, „This is somewhat like the temperature cycles in crystal quality control in industrial processes.“ A continuous supply of salt for the formation of the crystals was provided by the dissolution of anhydrite (the anhydrous form of calcium sulfate), the mechanism accounting for the formation of the large crystals of Naica.

Because of their purity, the crystals forming the geode cannot be dated precisely. But indirect constraint can be done: