... corundum, brown aluminium oxide, dull grain shape, top high toughness Description:AETL ... grains, we specially process the ingots, separate the magnetic material, and sieve the grains carefully to get a ... 2090 Knoop scale, 9.0 Mohs scaleMagnetic Material 0.0076%Grain Sizes Available (F):12, 14, 16, 20, 22 ... 60, 70, 80, 90, 100, 120, 150, 180.Grain Size Distribution :Upon ANSI B74.12-2001, FEPA-Standard 42 ...