Magnesium metal is a stable isotope that has found application in isotopic geology, similar like aluminum. Mg is a radiogenic daughter product of Al which has a life of 717,000 years. Large enrichments of stable Mg have been observed in the Ca-Al-rich inclusions of some carbonaceous chondrite meteorites. The irregular abundance of magnesium is attributed to the decay of its parent aluminum in the inclusions. So, the meteorite must have formed in the solar nebula before the Al had decayed. After that these fragments are among the oldest objects in the modern solar system and have preserved information about its early history.
It is conventional to plot 26Mg/24Mg against an Al/Mg ratio. In an isochron dating plot, the Al/Mg ratio plotted is 27Al/24Mg. The slope of the isochron has no age significance, but indicates the initial 26Al/27Al ratio in the sample at the time when the systems were separated from a common reservoir.
Magnesium isolation is present with next compounds. Magnesium can be made commercially by several processes and would not normally be made in the laboratory because of its ready availability.
CaO + H2O -> Ca2+ + 2OH-
Mg2+ + 2OH- -> Mg(OH)2
Mg(OH)2 + 2HCl -> MgCl2 + 2H2O
Electrolysis of hot molten MgCl2 affords magnesium as a liquid whit is poured off and chlorine gas.
cathode: Mg2+(l) + 2e- -> Mg
anode: Cl-(l) -> 1/2 Cl2 (g) + e-
There are other methods used to produce magnesium is non electrolytic and involves dolomite,
[MgCa(CO3)2], an important magnesium mineral. This is "calcined" by heating to form calcined dolomite, MgO. CaO, and this reacted with ferrosilicon alloy.
2[MgO.CaO] + FeSi -> 2Mg + Ca2SiO4 + Fe
The magnesium may be distilled out from this mixture of products.