About Travertine Blocks : The main difference between travertine and other natural stones lies in the formation of the rock, the hardness of the stone and its appearance. Travertine is a form of limestone deposited by mineral springs, particularly hot springs. It is formed by the precipitation of carbonate minerals from solution in ground and surface waters, usually at the mouth of geothermally heated hot springs or in a limestone cave. The main feature of travertine stone is the holes within the stone which are caused by carbon dioxide evasion. The quality and usefulness of the stone is often measured by the size and density of these holes. Higher quality Grade A Travertine has fewer holes. Usually the holes are filled with epoxy to match the color the stone and then further finished for the specific application i.e. wall cladding, kitchen and bath tile, floor paver, pool coping, etc.