The term onyx was once reserved for a type of agate, which is in turn derived from quartz. This form of onyx is almost exclusively black-and-white and is often used in jewelry. Most of the onyx found in home decor comes from calcite, a mineral that also forms the basis for travertine, limestone and marble. In fact, its resemblance to the latter is the reason why onyx is sometimes known as "onyx marble."
Like marble, onyx has a smooth, somewhat porous surface. It is also
similar to marble in that it has a fairly low density. This makes it
softer and more pliable than other natural stone tile, particularly
granite. It comes in a variety of mostly earth-toned shades and can be
finished in a number of ways, though it is typically honed or polished
to a high shine. How to clean Onyx Tile