I have been thinking about the washita thread, and realized that sometimes, depending on particle size, novaculite has been used to make arrow heads.. In fact some of the material is sold in knapping circles.
So taking this to another level, I wondered if other types of arrow head material might be suitable for sharpening... I have access to a considerable quantity of a flint from Georgetown /Austin Texas area called Georgetown blue...
So I cut a piece and lapped the surface to smooth it out, and here is a picture...A super knapping material, and based on my limited ability to sharpen knives , also a very fine grade of polishing. Not really sharpening unless you have no life and want to spend hours on a single blade, but interesting, at least to me.
So no surprise, I can not load the picture. Imagine a grey/dark grey flat maybe 9x8".