The Etruscans carved many of their works from tufa, a soft porous variety of this calcium carbonate rock
It is formed by a process of 
rapid precipitation of calcium carbonate, often at ... Travertine is a terrestrial 
sedimentary rock, formed by the precipitation of... [DOC] [TLE] download now - British Geological Survey [PAR] Click on this link to visit Worcestershire's geology and its contribution to known 
building stones, ...