Chemical Weathering!
The process by which the inside structure of a mineral is changed by the addition or removal of elements. Change in phase (mineral type) and composition are due to the action of chemical agents. Chemical weathering is weak on available surface for reaction temperature and presence of chemically active fluids. Smaller particle sizes weather by chemical means more rapidly than large particles due to an increase of surface area.
Watch this awesome video to find out how chemical weathering works!