im not sure why but there are a few materials used in crafting (you know they even say on them the disciplines they are used for and the level you use them at) but they cannot be deposited into the bank as collectibles because they dont have spots in their for some reason, the first thing that comes to mind is gold daubloons (and i assume silver and copper too) but their are others too
ANET plz make slots in the bank collectibles tab for more items like this that are clearly crafting materials