Messinian Gypsum

Its unique crystalline structure gives this rock a lunar appearance, which is why it is referred to as selenitic gypsum or selenite. The city of Bologna has strong links with this stone, which was traditionally used in large square blocks for the construction of the most important buildings during the Roman empire. The first ring of city walls around Bologna, built in the 3rd century A.D., was erected using blocks of gypsum: the “Selenite Walls”.