Magnesium chloride is a chloride chemical formula MgCl2 colorless and easily deliquescent crystal soluble in water Magnesium chloride hydrate can be extracted from brine or seawater usually with 6 molecules of crystal water but it loses crystal water when heated to 95C begins to decompose when it is above 135C and releases hydrogen chloride HCl gas Product Parameters TEST ITEMS TEST STANDARD MAGNESIUM CHLORIDE ANHYDROUS MAGNESIUM CHLORIDE HEXAHYDRATE MAGNESIUM CHLORIDEAs MgCl2 990 460 CALCIUM As Ca2 0002 015 SULFATE As SO42 100 ALKALI CHLORIDE As Cl 050 WATER INSOLUBLE 02 010 MOISTURE 02 FE 0005 NA 0002 MGO 05