Magnesium is a chemical element with
the symbol Mg, an atomic number of 12. It has an
atomic weight of 24.3050. 
Things you might not know about
Magnesium:
- Magnesium is the most abundant elements found
in the earth's crust.
- Magnesium is needed for more than 300
biological processes and a variety of functions in the human body.
It is used by the living cells to process and regenerate
energy
- Mixed with iron it is called thermite!
- The wick of a trick candle has small amounts
of magnesium in them. When you light the candle, you are also
lighting the magnesium. When someone tries to blow out the flame,
the magnesium inside the wick continues to burn and, in just a
split second (or two or three), relights the wick.
See GC2XAY2 - Hydrogen, for an explanation
about this series of caches.