I'm just going to reply to this thread for anyone that may be lookiing in SE wyoming in the future. I was just up on the south side of GreyRocks reservoir, checking out some rocks along the road right of way, and I found a gracious plenty of a couple of three types of chert. The cobbles that were right there by the road where they had tumbled down the hillside were not huge and ranged from golf ball sized pieces to one the size of a basketball and lots of cobbles of various sizes in between. I have only knocked off small pieces of cortex from most, and there is some grey, blackish, tan, and some beautiful tan to deep orangy red stuff. I picked up a good bit of each that I could see the core of that was broken off of bigger rock up the hillside, and some is glassy smooth while other is a bit grainy, but still very nice and knappable. I have no idea what I'm going to find as far as consistency within these rocks as far as cracks or concrete inclusion, but I'm stoked to find out. I'm hoping that heat treating will take care of some of the grainer stone, so I'm about to buy a turkey baster and will hopefully have this rock heat treated and worked some by next weekend. I'll post up pictures of how it turns out. This rock may not be anything folks on here would care to pick up and work, but I know for sure that skilled knappers could easily make some sweet points out of a lot of what I found.