If folks want to try a 'glass' knife", try West Desert Collectors This is a small rock shop, but the owner has a local guy that knaps all kinds of obsidian (Delta Utah has large obsidian fields nearby) to include arrowheads and knives. All first rate stuff. Picked up a flint knife for my Grandson there, very nice and had a 'primitive' leather sheath. High quality - what I would call almost 'museum quality' for very reasonable $$ -as we are "locals" Near Topaz Mt this lie on the ground the area is a rockhounds delight. Give the guy a call and see what he can do....
