Wow! You really put that stone to good use. Those are sweet!
The non-heat treated grey stuff is quarried Georgetown flint and was pulled out from deep deposits. It has a different workability than the surface-collected flint (the quarried is much easier to pressure flake). The heat-treated stuff is shinier than the raw.
Yeah the grey stuff pressure flakes like a dream ! That stuff isn't heat treated? I would not have guessed that. The brown type that looks like it comes from cobbles I would assume is heat treated. I have tried some of that cobble that I know wasn't heat treated and it was harder than my pecker in the morning!
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The brown rock reminds me of some rock we have in Tampa Bay called ledge (fossilized algae) I broke a couple bifaces it seemed susceptible to shock more than the grey stuff.
Well, they both were a pleasure to work much appreciated !