What is the correct name for a reaction like this?
$$ \ce{ 4MnO2 ->[500\ ^\circ \text{C}] 2Mn2O3 + O2 ^}$$
Is it a synthesis, or a Decomposition? I tried to find it out with http://en.wikipedia.org/wiki/Chemical_reaction but i did not get the link between the formula and the nomenclature as it seems to be both.