Polarised light micrograph of crystals of magnesium chloride (MgCl2). Typically, magnesium chloride forms complexes with other molecules; the hygroscopic hexahydrate MgCl2.6H2O is used in moistening cotton threads in spinning, with oxide chlorides (heat on these hydrates) being used in cements. Magnesium (Mg) is an alkaline earth metal, silver white and very light, and may be obtained by electrolysis of magnesium chloride. Magnification: x45 at 4x5 inch size.