Magnesium chloride is a chloride with the chemical formula MgCl2. It is colorless and hygroscopic. These salts of magnesium are typical ionic halides, easily soluble in water. Hydrated magnesium chloride can be extracted from seawater or brine. It usually contains six molecules of结晶水 (crystalline water). However, it loses its crystalline water when heated to 95°C. Above 135°C, it begins to decompose and releases HCl gas. It is an industrial raw material for producing magnesium and is found in seawater and brine.