OP, in the future that you should be doing is setting up a workbench and a chest atop each crypt, and ideally also have a portal terminus that you can move from crypt to crypt as you clear them. afterwards you and your wife can work your way back to each cleared crypt and collect the stored iron atop each crypt.

As for what the others have said, the only way you're getting that lost iron back is if you console it back in, because you let it despawn by tossing it onto the ground and leaving it there.