Miners drilling through limestone in Chihuahua, Mexico, broke into an extraordinary chamber in 2000 and found something that defied geological expectations: gypsum crystals taller than telephone poles ...

More than 900 feet beneath a mountain in northern Mexico, there’s a hidden chamber that almost doesn’t look real. Massive, glass-like crystals stretch in every direction, some as long as a city bus.

These huge gypsum crystals in Mexico's Naica caves, some up to 12m long, have been growing for tens of thousands of years -- but scientists have only now discovered what's inside them. "We've ...