The fifth coin looks like some of the silver I stored in pvc album pockets for nearly 40 years (not any more, I should add!), with a blue/green deposit caused by 'sweating'. It could just be the photos though. Accum, A quick dip in carbon Tet. will remove the green residue caused by polyvinyl sweating. Wear gloves though, it does not burn, but does absorb in the skin! If you can get hold of any. Wonderful solvent, but a no-no under H&S regs. It's fair to say that it's easier to list what it doesn't do.