Those were neat. I have a bag of obsidian that I want to make knife blades and arrow heads from but I'm afraid to start napping them. I've never
done it before and don't want to mess it up.
Sorry i missed your comment! You could start on glass - i have not worked obsidian yet, but glass is pretty much the same thing, as well as less
dangerous and it's ok to waste the stuff.
Look out for beer bottles, jars etc with a thick, flat ish base, and break that out by dropping a knife or penny in the bottle and shaking.
Then use an antler tine or sliver of bone to flake it.
Glass is great to learn on, i'd really recommend it... take a look at these..