There are a couple or three made of petrified wood (the only native stone around there with a concoidal fracture), the rest are bartered goods. There was a thriving trade with the Karonkawa(?) in central Texas for chert and flint. I had a friend who used to hunt in the San Rayburn area and used to find ones made of materials not found for 3 or 4 hundred miles from the area. Real unusual ones, petrified coral, quartz, and obsidian. One gorgeous spearpoint made from Llanite (I suspect that was made by a hobbyist though, because Llanite wasn't discovered till they cut through a hill to put in Texas HWY 77 in the fifties.