Close to Barbrook 1 stone circle is a reconstructed cairn, every time i go there i find more and more little bits of quartz and to be honest i don't mind that as they're usually hidden under the stones,
Possibly a bit anoraky, but quartz is often viewed as an important component of a site , being intentionally deposited in many cases .If the there hasn't been a record or excavation this might skew results .