Although composed of nearly horizontal strata of sandstone, Autana contains caves and other karst formations, which are rare in rocks other than limestones. These formations are the result of the dissolution of cemented sandstone which contain parts with certain ratios of limestone and parts with a higher proportion of calcium carbonate. This process leaves large empty spaces which in Cerro Autana form interconnected caverns and a lounge with a domed ceiling. This vaulted living room has two unequal openings that pierce the hill side to side and lean out as a form of balcony in the vertical walls of the mountain. One of these openings, although elongated, is so small that it is indistinguishable from below. Some of the cavernous passages have collapsed in recent years. A particular alumino-nitrate found in the main cave is sveite, named after the Sociedad Venezolana de Espeleologia whose members collected the first samples.