travertine
Concise Oxford English Dictionary © 2008 Oxford University Press:
travertine /ˈtravətɪn/
▶noun white or light-coloured calcareous rock deposited from mineral springs, used in building.
– origin C18: from Ital. travertino, tivertino, from L. tiburtinus ‘of Tibur’ (now Tivoli, near Rome).
'travertine' also found in these Oxford entries:

