A rare glimpse of the cave of crystals

From the BBC website: http://news.bbc.co.uk/1/hi/sci/tech/8466493.stm

Mexico's Cave of Crystals stunned geologists when it was first discovered in 2000. The underground chamber contains some of the largest natural crystals ever found - some of the selenite structures have grown to more than 10m long. Professor Iain Stewart got a rare glimpse of the subterranean spectacle while filming for the new BBC series How the Earth Made Us. Read the article on the BBC website.