What is this?

[hillrat]

Explosive? Ok. So, my friend is walking around up above an abandon mine in Nevada, and he finds what looks like a core sample. Only it's not round, it's sort of almost round. And it's been drilled into, and has this thing stuck in it. His wife thinks it's an explosive of some kind, he doesn't. I don't know, so I thought I'd ask around here. Though it doesn't really look like a blasting cap to me (based on what I've seen), I wouldn't bet my life on it.
Anyone recognize it?