For some reason... unknown to me... there isn't a solid resource to be found about where I can actually find chert, flint, or obsidian. I have found only one piece of advice: near water.
I am wondering if anyone has a few tips about whether or not stones for flint knapping can be found in any region of the United States and, if so, where the material occurs. I know it's a type of dense sedimentary rock, composed mostly of quarts, which has fine crystal structure and behaves as if it has none, like glass. I know it is probably found near water, but should I be looking near the mouth of a river, the edge of a lake, the bed of a river, or just anywhere that contains a lot of stone?
I would like to practice some flint knapping, but find the idea of buying a rock to be a little... ridiculous, especially for somebody just looking for some first-time practice.
If it depends on the region, then specify to southwest of Lake Michigan, specifically northern Illinois.