A sintered, generally spherical ceramic body, having an alumina content of from about 52 to about 58 weight percent distributed substantially homogeneously throughout the body, a silica content from about 32 to about 39 weight percent distributed substantially homogeneously throughout the body, an apparent specific gravity of about 2.63 to about 2.67, and a bulk density of about 1.48 to about 1.56 grams per cubic centimeter.