I am with Twisted Limbs, definitely not not Rainbow Obsidian, I don't think it is obsidian at all, like Twisted Limbs said. But that being said, Very nice work, irregardless of material!
![Cool 8)](http://www.primitivearcher.com/smf/Smileys/default/cool.gif)
Sinew would look better, but what you have is fine as far as I am concerned, I am a firm believer in using what you have at hand, and doing the best you can with it. You did fine!
![Wink ;)](http://www.primitivearcher.com/smf/Smileys/default/wink.gif)
Nice knife.
Wayne