Alumina, or aluminum oxide, with a molecular weight of 102, is the major source of aluminum in nature. Alumina (Aluminum oxide) has a very high melting point of 2,072 °C and it is extremely hard.  Alumina ceramic is the most common technical material and relatively traditional ceramic.  High purity alumina has excellent performances in electrical insulation, high chemical resistance, and low thermal expansion.  They are used to make parts for CVD, ion implants, photolithography, and semiconductor.  Alumina tubes are used for industrial furnaces and thermal couple protectors.  Alumina ceramics are ideal for products such as injector tubes, gas nozzles, and insulators traditionally.  The high hardness makes alumina an ideal material for abrasive, grinding media.  Alumina mortars and pestles are widely used in laboratories for grinding.