PURPOSE: To obtain a sol-gel abrasive grain which has an extremely advantageous friability which enables production of a product suitable for low-pressure grinding, by quenching sol-gel alumina grains and inducing the formation of a specific amount of microcracking.

CONSTITUTION: This sol-gel alumina abrasive grain has about from 10 to 200 microcracks per 1 mm2 of the grain surface. A grain with a preferable microcrack has a grit size of 50 grit or smaller. Microcracks most appropriately are uniformly distributed over the whole grain surface in the form of an interconnected network. Microcracks are formed, for example, by heating a sol-gel alumina abrasive grain to an elevated temperature and then quenching it by lowering the temperature by from about 200 to about 1,000°C. A preferable quenching is carried out by lowering the temperature by from about 250 to about 500°C. The quenching medium is preferably water, more preferably brine, as the heat capacity is larger than that of water alone.