I heat treat our local raw flint (chert) in order to bring out color and to make the texture more glass like for knapping. A friend has a kiln for that purpose, but it can also be done in the aboriginal manner by digging out the sand in your fire pit and laying down the flint. Then cover the flint about two inches with sand and build your camp fire. One treatment with a good fire usually brings out the red color range from the iron naturally occurring in the rock.
I once asked my friend to heat a head size piece of agatized coral I had gotten out of the Withlacoochee river. Unfortunately the rock was not solid and had a hidden geode which must have been full of water. When he heated it the geode exploded and destroyed the kiln.
Thanks to all for the kind words..Geo
