Apatite, Phosphorite and Phosphate Rock Geology. Apatite is the mineral used for the hardness of 5 in the Mohs Phosphate rock and phosphorite are names used for sedimentary rocks that contain at least 15% to 20% . Hardness Of Phosphate Rock For Grinding . Hardness Of Phosphate Rock For Grinding,Vertical Roller Mill Sale Supplier.