After a period of use, if not well waterproofed, water and dirt will penetrate the stone, causing stains and affect stone surface. Natural stone are natural material with high porosity and water absorption from 0.5% to 3-4%. So inorganic and organic stains from industrial or living wastes accumulate on the surface or in the pores of stone are environments for growth of bacteria which can destroy stone by their acids.
Corrosion of natural stone can be caused by chemical reactions which occur when stone is in aquatic environment contains large concentrations of carbon dioxide or other acids. Besides, stone contains many different minerals, therefore, if there is irregular thermal expansion, stone will also be adversely affected.

If being soaked for long time, the color of natural stone will  change and fade or even discolorate.