Physicochemical Properties: White crystalline or powder; and its aqueous solution show alkaline reaction; 2.36g/cm3. It is soluble in diluted acid and ammonium salt solution and almost insoluble in water and alcohol. Its solubility (18)in water is 0.0009g/100g. It is easy to absorb carbon dioxide in the air. When it is heated to above 200℃ in alkaline solution, it will become hexagonal crystal system crystalline. At 350℃, it shall decompose into magnesium oxide and water, and change into magnesium oxide by losing water above 500℃. Use: The main constituent of this product (flame retardant) is the magnesium hydroxide, which is a kind of new-type stuff flam retardant and is universally used in polymer materials of rubber, chemical industry, construction material, plastic (polypropylene, polyethylene, PVC and EPDM, etc.), electron, unsaturated polyester, painting and dope, especially in the ventiduct coating cloth for mining, PVC unitary-core convey belt, flame retardance aluminum-plastic plate, flame retardance tarpaulin, PVE wire and cable material, cable sheath for mining, etc., which has the function of smoke-abatement and static resistance with the good effect of flame retardant, can replace the aluminum hydroxide.