Had a similar scare last year with resin fumes. Installing a proper exhaust fan made all the difference, pulling the bad air straight outside. Cleared the studio up in minutes and gave me real peace of mind.

Is your uncle really excited about it? That's so tough when someone gets their hopes up like that. I've picked up so many cool looking, heavy black rocks myself, totally convinced until I looked closer. They always end up being just lumps of slag from some old factory. Maybe you can gently tell him to look for that smooth, dark crust instead of the bubbly glassy stuff. It's a bummer, but hey, maybe next time he'll find a real one!