Nano-sized alpha alumina particles having a silica coating thereon

A process for the production of fine alpha alumina particles having a silica coating thereon which comprises dispersing silica in a gel of boehmite particles with a particle size less than about 100 nanometers in an amount that represents from about 0.5 to about 5 wt. % of the solids content of the gel, firing the resultant gel for a time and at a temperature sufficient to convert at least 80% by weight of the boehmite to alpha alumina in the form of loose agglomerates of primary particles but insufficient to cause the particles to become highly sintered, and thereafter comminuting the agglomerates of primary alpha alumina particles into a powder comprising individual particles of alpha alumina with particle widths of from about 20 to about 50 nanometers and a BET surface area of at least 50 m.sup.2 /gm.