A crystalline Boehmite product and a method of forming said product is provided in which the crystalline Boehmite exhibits an average particle size (d50) that is less than 7,000 nanometers. This method comprises preparing an aqueous slurry by mixing together water, large aluminum oxide precursors, a highly dispersible Boehmite grade, and optionally, an organic dispersing agent; adjusting the pH of the slurry; heating the slurry for a predetermined duration of time; collecting the slurry to form a wet cake; and drying the wet cake to obtain the crystalline Boehmite product. The crystalline Boehmite product may be mixed with a plastic resin to form a flame retardant plastic mixture, which can be subjected to a conventional plastic processing method to form a flame retardant composite.