now I'm really puzzled. I thought obsidian was basically volcanic glass. Can glass be magnetic?? So cool!

Today I visited one of my favorite antique stores, and found a necklace on a rack that I wanted to buy.. When I tried to take it off the rack to look at it more closely, suddenly all the necklaces next to it got tangled up together with mine. A salesperson was helping me, and we couldn't figure out what was going on until we realized all the necklaces were stuck to a bracelet (underneath the rack) with black stones in it that was magnetic!

Must have been the same material. Maybe I'll go back and take another look at it.