Cave of the Crystals

Cave of the Crystals or Giant Crystal Cave is a cave connected to the Naica Mine at a depth of 300 metres, in Naica, Chihuahua, Mexico. It takes the form of a chamber within the limestone host rock of the mine, and is about 109-metre long with a volume of 5,000 to 6,000 cubic metres.The chamber contains giant selenite crystals, some of the largest natural crystals ever found. The largest is 11.40 metres, with a volume of about 5 cubic metres, and an estimated mass of 12 tonnes.