Classification and tipology of stone

Usually the natural stones are divided into:

MARBLES: Rocks compact suitable to be polished;
GRANITE: Rocks tough-looking granular;
TRAVERTINI: Rocks porous easy to work;

For outdoor use stones with a compact and homogeneous structure are more suitable, because they tend to withstand better climate change; for indoor use marble, which offer a wider array of colors and shades, are the most used.