... ,F20,F22,F24,F30,F36,F40,F46,F54,F60,F70,F80,F90,F100,F120,F150,F180,F220 Grits NO:cumuli densityGrits ... .63-1.72 F221.88-1.98 F1001.63-1.71 F241.87-1.97 F1201.60-1.70 F301.83-1.93 F1501.58-1.68 ... F361.82-1.92 ... F1801.58-1.68 F401.78-1.88 F2201.58-1.65magnetism ...