The cargneule, a carbonate sedimentary rock, with a decayed and frequently brecciated appearance, often takes on yellow, brown or rusty hues. The cargneules form lightly stratified or unstratified masses and give ruiniform reliefs. Ÿou can see these towers before you, evocative of ancient castle ruins. The transformation of dolomite or limestone into calcite by waters loaded with calcium as a result of the dissolution of gypsum is called cargneulisation. (CaSO4 → Ca2+ + SO4-2).