The present invention provides an aqueous slurry composition that comprises cerium oxide and/or cerium oxide-containing mixed rare earth oxide abrasive particles, a polyacrylate, and an agent that retards hard settling. The agent that retards hard settling is preferably a polysaccharide such as xanthan gum, microcrystalline cellulose and/or sodium alginate, the latter of which may be treated with a divalent metal salt such as calcium carbonate. The slurry composition according to the invention can be used to polish glass and glass ceramics at a high removal rate, but does not hard settle upon extended static conditions and can be easily resuspended. The present invention also provides a method of polishing a glass or glass ceramic substrate using the slurry composition.