Octavian Anton, Dirk Van Wouwe: Synthetic crystal aggregates of xonotlite and process for preparing same. Redco, Wegner & Bretschneider, July 18, 1989: US04849195 (2 worldwide citation)

In synthetic, substantially spherical crystal aggregates of xonotlite having a particle size of more than 20 microns, and preferably up to 150 microns, up to 30% of the silicon atoms can be replaced by titanium or zirconium atoms, and inert particles can be incorporated in the crystal aggregates.

Octavian Anton, Dirk Van Wouwe, Georges Poncelet, Pierre Jacobs, Johan Martens: Silica-particles containing alumina, process for preparing same and the use thereof. Redco, Wegner & Bretschneider, January 19, 1988: US04720475 (1 worldwide citation)

Amorphous, substantially spherical silica particles obtained by acidic hydrolysis of substantially spherical synthetic crystalline calcium silicates having a size of from 20 to 120 microns are coated with a layer comprising silica and alumina. The silica particles obtained may be directly employed a ...