Archaeologists spotted fragments of quartz called 'rock crystal' at the site ... that these materials were brought from either a cave in the mountains of Snowdonia in the north of Wales or ...

The Cave of Crystals, also known as the Giant Crystal Cave, is a cave connected to the Naica Mine at a depth of 300 meters (980 ft) in Naica, Chihuahua, Mexico. It takes the form of a chamber ...

More than one of our readers suggested we highlight this beautifully-shot process documentary about the laborious and precise manufacturing of piezoelectric quartz crystals in the early 1940s.