Clay is ground to a particle size of -14 mesh and during agitation is treated with a fine mist of H2O in an amount sufficient to form compact surfaces without causing agglomeration. The mist-treated clay is dried at 100 deg - 350 deg C to cause the particles to shrink and harden. The particles are calcined and then leached with an inorganic acid to extract the Al. Because of the treatment with a mist of H2O, the solid material remaining has a greater sedimentation rate and is more permeable to H2O. Thus, a clay not treated with an H2O mist gave particles that had a fuzzy surface when calcined at 750 deg C, 5.7-10.8% fines during fluidized-bed roasting, and a density of 0.95-0.99 G/Cm3. The sedimentation rate was 4.0-14.3 Cm/min and permeability to H2O on a buchner funnel (5.8- 11.0)X10-8 Cm3 of the solids remaining after leaching with HCl. The respective values for clay treated with a mist of H2O were 1.7, 0.99, 16.2, and 11.2X10-8 and the calcined particles had a dense compacted surface.