Magnesium oxide powder is a white powdered mineral that is a source of magnesium. It is also called Magnesia or MgO. It is used as an insulation material in various types of temperature sensor such as mineral insulated thermocouples. Magnesium oxide powder is tightly packed to provide electrical resistance and protection to the temperature sensor wires. It has become the standard powder insulation for temperature sensors and can withstand very high temperatures.