Good to know. In geological terms 9,000 years is not that long ago even if it is seriously ancient to us (that is all I meant by relatively recent). What led me to ask about it is that I can find natural flint pieces around here that may show some discoloration over time (evident if you break it, or if it has a fresh break) but not nearly as extreme as that piece. It seems like the banded flint specimens I find would have faded to white if they were at Americus' location. Anyway I did not mean to derail this thread, thanks again for the info.