Stone is Absorbent

Although we usually think of stone as "hard," it is a porous material. Natural stone has varying degrees of porosity depending on the type of stone. If left unsealed, spills and everyday messes can easily penetrate the surface. The liquid eventually evaporates but the stain is left behind.

Highly acidic substances such as orange juice, coffee and wine will also etch acid sensitive stones and leave a dull mark. Acid resistant stones such as most granite, slate and sandstone will not etch.