I shouldn't be able to knap a hard rock with a soft rock

[Moa]

I have discovered that, although I can't make a tool out of a soft rock like claystone, I can put a piece of flint or granite down as a knapping surface and use claystone to knap it. This shouldn't work, because the claystone is softer than the flint/granite/whatever. And if it does somehow work anyway, the claystone should at least be destroyed.

[cjameshuff]

Knapping can be done with tools made from wood and antlers, it's not just a matter of the hardest material winning.