Sedimentary mica flakes are produced having a bulk density of between about five and one-half pounds per cubic feet and eight pounds per cubic feet (5.5-11 lbs/ft.sup.3), a high aspect ratio, and a G.E. brightness between about seventy-five and ninety (75-90). Operations include applying shear forces to delaminate the mica into flakes. Shear forces are applied by rotating a plurality of arcuate blades within a confined chamber containing the mica, such that the mica is forced between an outer portion of each blade and said chamber. The resulting delaminated mica flakes may be dried and classified.