Originally posted by Jeff:
brightnorm,
I'm not as skilled with the vowels and consonants as darell but here goes.
An Arkansas stone is used primarily by gunsmiths and for sharpening knives. It's a hard white stone but I don't know if it's harder than a file.
It removes very little material per stroke and it certainly isn't as aggresive as a file. You might say that the file is used for the initial rough work and the stone finishes it off. It produces a finish similar to polishing metal with #0000 steel wool.
They're not expensive (a few $) for a small one and $15-20 for a large one.