A lot of those places are just plain out reduction sites. I live on one. You find all the stuff they left behind they couldn't use. In that mess you find a lot (A LOT) of broken preforms. And since it is quartz, it is most times really hard to tell if it was part artifact or JAR. I use my preponderance of the eveidence theory. If I keep finding the same piece of quartz with the same notches, curvatures, etc. cut out the same way, then somebody was trying to to something. In the end, its just cool that they were mining there. I've found so many that were in a certain form when they broke, I can tell exactly how they went about working it to get it to something they could finish. And from all the different lithic types I find on my place, I think the site was mined for thousands of years.