Cave of the Crystals Cueva de los cristales Gypsum crystals in the Naica cave. Note person for scale Location within Mexico Location Naica , Saucillo Municipality, Chihuahua, Mexico Coordinates 27°51′3″N 105°29′47″W / 27.85083°N 105.49639°W Length 109   m (358   ft) Discovery 2000 Geology Limestone Hazards High temperature and humidity Access Currently inaccessible Cave of the Crystals ( Spanish : Cueva de los cristales ), also known as Naica Cave ( Spanish : Cueva de Naica ) or the Giant Crystal Cave , is a cave connected to the Naica Mine at a depth of 300 metres (980   ft) , in Naica , Chihuahua , Mexico . It takes the form of a chamber within the limestone host rock of the mine, and is about 109 metres (358   ft) long with a volume of 5,000 to 6,000 cubic metres (180,000 to 210,000   ft 3 ) . [ 1 ] The chamber contains giant selenite crystals ( gypsum , CaSO 4 · 2 H 2 O ), some of the largest natural crystals ever found.…