Granite Mortar and Pestle

Granite is a common type of intrusive, felsic, igneous rock which is granular and phaneritic in texture.
A worldwide average of the chemical composition of granite, by weight percent:

 

SiO272.04% (silica)
Al2O314.42% (alumina)
K2O4.12%
Na2O3.69%
CaO1.82%
FeO1.68%
Fe2O31.22%
MgO0.71%
TiO20.30%
P2O50.12%
MnO0.05%

It is not easy to measure the hardness of Granite. Granite is a rock composed of multiple minerals, typical Quartz, Feldspar, Biotite and Hornblende. Each of the minerals has a unique hardness. In other words, we can measure the hardness of individual material but not easy of granite as a rock.