Description: Wollastonite, a natural calcium silicate mineral, is unique among soil amendments as a source of silicon and carbon-neutral calcium. HK products are made by crushing, drying and milling the wollastonite ore. The same ore is used for all grades, which differ only in particle size distribution.It is milled natural ore. Our advantages: 1.lower Fe content 2.lower LOI 3.higher whiteness 4.chosen by manpower 5. we can also choose the mineral according to the clients specific requirements. Parameters: Item Typical Value SiO2 (m/m,%) 50%min CaO (m/m,%) 43%min Fe2O3 (m/m,%) 0.5%max MgO (m/m,%) 1.5%max LOI. 2%max Whiteness 88-90 Shape Powder  325 Mesh