I pass these rocks every time I go to the hardware store, which, since we just bought an older house in need of considerable work, is fairly frequently. I often wondered what was inside the nearby rock store, and finally made the stop to check it out. What a museum of geology is inside there! - a veritable treasure trove of rocks, crystals and gemstones. Since you are stopping for this cache, wander around the rock yards inside and outside of this store. It's worth a stop - better than a geology museum and free!.