Yes. Saw an article a few years back on Tenochtitlan, and obsidian was indeed a significant trade item. One can grind it up, run it through some high end lab equipment for elemental assays and then identify the material's root source. Had some guys through here about 20 years back asking for locations and then sampling/assaying our sources. Some of our materials were traded clear across to the east coast. If one finds foreign sourced but finished products, then the points were traded for. If on finds piles of flakes, then the raw materials where shipped in and shaped on site.
We have 8 or 9 locations in our county where one can gather 100 lbs in about 5 minutes or so on public lands. Quite a variety of colors and various degrees of clarity. With our better materials one can see through chunks that might be 1 to 2 inches thick. If I could backlight about 1/2 of the points in that image above, the transparency would be obvious, but it does not show once pieces are placed on a flat surface. We have softball sized cobbles in our yard and around the property. Adequate material, but not the really good stuff that's available if I travel 15 or 20 miles. About 100 miles away near Paulina Lake there is an obsidian flow with car sized boulders scattered about. It's a Park setting, however, and they discourage taking. Not an issue for me, as it's really not good stuff anyway. I've seen a bit in Yellowstone Park, but it too is pretty poor grade.
If one gets near a few of our good sources and near water, he can find chipped off detritus a few feet deep in some instances. For trading or transport purposes is was far lighter to haul around roughed out preforms than a bag full of cobbles.
We don't have any nearby flint given the volcanic history of the PNW, but with a little surfing one can shake out a lot of the famous sites for flint in the Midwest and East. Deeded property, however, usually makes its acquisition a bit of a money deal.
