Stone-cancer (as stone-leprosy) of Taj Mahal is due to formation of

Taj Mahal is made of marble (white stone), chemically it is CaCO3. Acid rain corrodes marble. In presence of H2SO4, marble from the surface gets converted into CaSO4 (gypsum) which has 2.1 times greater volume than marble, which causes increase in pressure on the surface of marble which leads to peeling, pitting and corrosion. This is called 'stone-leprosy' or stone-cancer.SO2 + O2 →   SO3SO3 + H2O →   H2SO4Acid  rainCaCO3Marble  ofTaj  Mahal  +  H2SO4  →   CaSO4Stone − cancer +  H2O + CO2