Subject: Why does magnesium have such a low melting point?

'The Revised Nuffield Advanced Science Book Of Data' lists the melting / 
freezing points of the Group II metals as follows:

Be - 1551K
Mg - 922K
Ca - 1112K
Sr - 1042K
Ba - 998K

As you can see, there is a general decrease in melting point corresponding
to decreased forces of electrostatic attraction between the metal cations
and the delocalised electrons of the metalic bond as we move down the
group. However, the melting point of magnesium is unexpectedly low. Why 
is this?


All three chemistry teachers at my school and the 'Ask-A-Teacher' service
on AOL couldn't give me an answer! 

Thanks!

Re: Why does magnesium have such a low melting point?