Marble is a metamorphic rock. Metamorphic means “changed”. It starts out as a Limestone, Travertine or even Sandstone. After exposure to high temperatures and pressure, the result is a much more dense and less porous stone. Marble and Granite are the stones with the most variety in color. Unlike Granite, Marble is a softer stone and very susceptible to scratching, etching and sometimes staining.
Marble had several different uses in ancient times. It was used for almost every building. Now it is most commonly used for flooring, counters and tables. It can also be used for showers and wall tile. Marble is usually sold polished, but unsealed.
Marble is also sold tumbled. Tumbled Marble is put into a vibration machine that beats up the surface to a dull appearance that is generally uniform in color but more porous. Installation can be very rough on Marble, so it is very common that a new Marble floor will need to be re-polished and re-sealed. Only non-sanded grout should be used to avoid scratching. Marbles to avoid: green and black varieties. They show scratches and etching more than lighter shades and can be very difficult to restore.