Grade1 Extra Fine Grade 2 Grade 3
SiO2 62.16 % 61 - 62.5% 60 - 61.5%
MgO 31.54 % 31.5 - 32.5% 30 - 31.5%
Fe2O3 0.15 % 0.01-0.2% 0.05-1%
Al2O3 0.32 % 0 - 1% 0 - 1%
CaO 0.43% 0 - 0.5% 0 - 1%
Average 96.6 % 92+/-2% 88+/-2%
Whiteness: