Travertine 

Travertine is created by hot springs, which dissolve the underlying rock, including limestone, and it forms on the surface inlayers as the water evaporates. The characteristic holes in travertine are caused by gas bubbles, trapped as the material hardens. Crosscuts are created when a block of limestone, travertine, or marble is cut across the vein rather than with it, giving a flowered look to familiar materials. Like all other stones, these will show a range or variation in color and pattern, and each tile or slab installation is unique. For the proper care of limestone and travertine, a routine sealing and maintenance program should be adhered to.