Calcite/Travertine ("Onyx") Slabs from Arizona and New Mexico
Travertine cuts quickly and produces interesting stones. Travertine is often incorrectly called onyx, but it is not a true onyx, which is a form of chalcedony. These materials may have fractures, but usually they don’t cause problems when cutting. Polishing calcite and travertine is quick if you add a little vinegar to tin oxide. Green rouge (also known as Zam) provides a fine polish as well.