The Marble Caves is geological formation of unusual beauty. These caves have formed in a pure marble and are bathed in the deep blue water of General Carrera Lake. Chile, the Marble Caves are some of the most impressive attractions of Patagonia.
Cave of the Crystals or Giant Crystal Cave is a cave connected to the Naica Mine 300 metres ft) below the surface, in Naica, Chihuahua, Mexico. The main chamber contains giant selenite crystals (gypsum, some of the largest natural crystals ever found.