Travertine is a form of limestone, a terrestrial sedimentary rock, formed by the precipitation of carbonate minerals from solution in ground and surface waters. Travertine often has a fibrous or concentric appearance and exists in white, tan, and cream-colored varieties. It is formed by a process of rapid precipitation of calcium carbonate, often at the mouth of a hot spring or in a limestone cave. In the latter, it can form stalactites, stalagmites, and other speleothems. ORIGIN late 18th cent.: from Italian travertino, tivertino, from Latin tiburtinus ‘of Tibur’ (now Tivoli, a district near Rome).