History

The Naica mine has been operational since the late 19th century, extracting lead, zinc, and silver from the limestone hills of the Chihuahuan Desert. In 1910, workers discovered a smaller crystal chamber near the surface — the Cueva de las Espadas (Cave of Swords) — containing selenite crystals up to 2 metres long. It was sealed to protect the formations.

On an unrecorded date in 2000, two brothers working as miners for the Penoles company were drilling a new tunnel at 300 metres depth when they broke through a wall into a chamber no human had ever entered. Their headlamps illuminated a cathedral of translucent crystal beams — some stretching the full height of the chamber, glowing amber and white. The chamber was approximately 30 metres long and 10 metres high.

The discovery was reported to the company and then to scientists. Mexican geologist Juan Manuel Garcia-Ruiz led the investigation that established the crystals growth mechanism: the cave had been filled with mineralised water at exactly 58 degrees Celsius for hundreds of thousands of years, slowly depositing selenite (crystalline gypsum) on the cave floor and walls. The water temperature was just below the threshold at which selenite dissolves back into solution, so crystals grew instead of dissolving — the longest-running crystal-growth experiment in geological history.

In 2017, Penoles ceased operations at Naica. Without the pumps running, groundwater flooded the cave again. The crystals, exposed to air for 17 years, may have suffered micro-fracturing and surface damage. Scientists retrieved sediment cores before the flooding and found something extraordinary: dormant microorganisms living inside the crystal matrix itself — extremophiles trapped 50,000 years ago, viable when cultured in the laboratory.