I'd put it under a microscope or eye lope.

It might be a heavy mineral like Lapus, or some of the coppers.
It needs to be examined by a pro or just yourself. It might
be a composite mixture like a sealing that is covering up something
nasty like tracer bullet. Burn anything.

I'd be careful, but likely it has been already been iD'd by doctors
or else. Maybe not if in the field...

We need more than color and a bullet - German is a big hint - all
sorts of this and that were tried.

Might be a sniper ID. Our bullets are marked with outside rings of
color and some colors indicate core content. But our bullets are FMJ.

Martin

On 11/12/2015 12:04 AM, wrote:
A friend has the bullet that was removed from his dad in WW II. 8mm
German; it has a blue core. What would that core be?