Travertine

Travertine, a natural stone, is a white concretionary form of calcium carbonate that is usually hard and semicrystalline. It is deposited from the water of mineral springs (especially hot springs) or streams holding lime in solution. When carbon dioxide-rich water percolates through earth and rocks in limestone areas, the water dissolves the limestone and becomes saturated with it. When the water resurfaces later, the sudden drop in pressure and the change in temperature cause the water to release the carbon dioxide gas, much like fizzy drinks. The limestone then recrystallizes, often over minute underwater plants. With time, the mineral deposits harden and become stone.

Extensive deposits exist at Tivoli, Italy, near Rome. In fact, travertine derives its name from this town. Tivoli was known as Tibur in ancient Roman times. The ancient name for the stone was lapis tiburtinus meaning tibur stone, which has been corrupted to travertine.

The largest building in the world constructed largely of travertine is the Colosseum in Rome. Another notable building using travertine extensively is the Getty Center in Los Angeles, California. The travertine used in the construction was imported from Tivoli. The website of the Getty Center contains more information about the use of travertine in its construction, including some videos of travertine being quarried and cut for use. The stone is most widely used in Italy, Greece and Turkey.

Travertine is one of several natural stones that are used for paving patios and garden paths. It is sometimes known as travertine limestone, sometimes as travertine marble; these are the same stone, even though it is neither limestone nor marble. The stone is characterised by pitted holes and troughs in its surface. Although these troughs occur naturally, they suggest to some eyes that considerable wear and tear has occurred over many years. Some installers use a grout to fill these holes, whereas others leave them open — travertine can even be purchased "filled" or "unfilled." It can be effectively polished to a smooth, shiny finish and comes in a variety of colors from grey to coral-red. Travertine is most commonly available in tile sizes for floor installations.

From Wikipedia