Travertine
  |
Travertine is a white concretionary form of calcium carbonate that is usually hard and semicrystalline. It is deposited from the water of mineral springs (especially hot springs) or streams holding lime in solution. Extensive deposits exist at Tivoli, Italy, near Rome. The largest building in the world constructed largely of travertine is the Colosseum in Rome, Italy
da:frådsten
de:Travertin
fr:Travertin