Magnesium is the 3rd most abundant element found in sea water, and so one of the main isolation procedures used to isolate magnesium use sea water as a source. The first step of this isolation process involves adding calcium carbonate to the sea water to form a precipitate of magnesium carbonate. The magnesium carbonate is not soluble in water, so it is filtered out and then reacted with hydrochloric acid. The second reaction with hydrochloric acid produces magnesium chloride. Pure magnesium is separated from the magnesium chloride compound through electrolysis.
Another isolation magnesium procedure uses dolomite. Dolomite is a sedimentary rock/mineral that is composed of calcium magnesium carbonate; therefore, dolomite is an important resource of pure magnesium. In this isolation process, the dolomite is heated to form calcined dolomite. The calcined dolomite is then reacted with ferrosilicon allow. The final distillation step is used to remove pure magnesium from the end products of this reaction.