I collect this material whenever I see it. I usually see it down in Ayrshire, Scotland, where I regularly go to look at interesting rocks.

This Flint slash chert (chert for Americans) takes a beautiful polish. I have tumbled it up many times. It has enough chalcedony in it that it takes that agate shine. The hardest part is splitting the rocks down to tumbler size. The hardness is a Mohs 7 so a hammer and force or a saw is needed.

Of course, the main use for this toffee colourrd Flint is as a Knapping material. Our ancestors would make arrowheads from this material. It can be split in such a way that a Flint knife can be sharper than a steel blade, although it is less durable.

The Flint in the UK tends to form out of old organic matter settled in the chalk beds off the coast. Much of the Flint you find in the UK contains some form of fossil. I don't see obvious fossils in this piece but I do see an agate eye on top there. You should be able to see it in the pics.

Estimated age is literally hundreds of millions of years old.