Mono-crystalline aluminum oxide is electro-fused mono-crystalline alumina abrasive produced by fusing calcined alumina by the Bayer's process in the producing process, and then by crushing and sizing to desired grain size. It has high hardness and unique micro fracturing containing of well grown micro corundum crystalline structure which generates many new cutting edges. It is suitable for a wide variety uses from general grinding to precision grinding of high hardness tool steels, etc.