Travertine is a terrestrial sedimentary rock, formed by the precipitation of carbonate minerals from solution in ground and surface waters, or geothermally heated hot-springs.[2][3] Similar (but softer and extremely porous) deposits formed from ambient-temperature water are known as tufa.
https://en.wikipedia.org/wiki/Travertine
But surely travertine is a metamorphic rock?Travertine is a variety of Marble, right? And isn't Marble a metamorphosed limestone?
My last geology course was in 1972...