Physically, commercial granites are hard, compact rocks with fine to coarse grains of metamorphic or igneous origin. Hardness: 6 to 7 on moh's scale Density: 2.6 to 2.8 kg/cm3 Compressive strength: 140 to 210 n/mm2 Modulus of rupture: 15 to 25 n/mm2 Water absorption: 0.1-0.6% Average wear: less then 1% Porosity: quite low Weather impact: resistant Chemically, they are igneous/metamorphic rocks composed of quartz, feldspar & ferromagnesian minerals like kriolite, chlorite, garnet, etc. A typical granite will have following chemical composition: Silica (sio2): 70-75% Al2o3: 10-15% Cao+mgo: less then 0.5% Feo + fe2o3: 2-4% Alkalies: 4-6% Tio2: less then 0.5% Loss on ignition (loi): less then 0.5%