Is light burned magnesium

It's different.
Light burned magnesium oxide (MgO), also known as magnesia, is commonly known as magnesite, light burned powder, and magnesium oxide powder. Density 2.94, light yellow or white powder. Melting point 2852 ℃, boiling point 3600 ℃. Soluble in acids and ammonium salts, insoluble in water and ethanol.
The specific surface area is 180m2/g at a calcination temperature of 400 ℃. At 1300 ℃, the specific surface area is only 3m2/g. Easily deliquescent in the air. It belongs to the category of gas hard cementitious materials.
Light burned magnesium oxide, also known as caustic clay or activated magnesia. It is a light burned magnesium oxide obtained by calcining natural magnesite, brucite, and magnesium hydroxide Mg (OH) 2 extracted from seawater or brine at temperatures ranging from 700 to 1000 ℃.
The molecular formula of active magnesium oxide is MgO, with a relative molecular weight of 40.30. Due to the high activity of this magnesium oxide, it is easy to absorb water and sometimes requires chemical treatment to protect it.