This sounds like an instant legend to me. First aid men in a mine will carry morphine, and maybe in an american silver mine they carried it in a special metal box such as the one described at the website - but I do not see miners carrying suicide kits, and I've known a lot of them in the UK - it doesn't ring true. If I was told a story that - "miners carry morphine to kill themselves with, just in case" I would make bloody sure I knew it was true before libelling them by writing a song about it.

Cheers
Ray