The extent to which abrasive grains break or split apart upon impact or under pressure; friable abrasives fracture relatively easily and posses a shorter lifespan.
Friability essentially means crumbability. That is to say that a substance can be reduced to fibers or finer particles by the action of pressure on its mass. The term is commonly used in reference to asbestos which is brittle enough to be reduced to small particles upon application of pressure.