I found this rock in my backyard. About a full hand size, a few pounds. light beige colored on the outside. Smooth and wore down so I couldn't see how it would flake. When I hit it with my file it sparked. When hit with a small riverstone, I got something that looks like large flakes. Inside was dark brown and some black. Got lots of step fractures, but lots of material. Would you call it flint, and would I be able to knap it? Do I need to heat treat it if you can tell? Also, how would I get some larger 'spalls' than what I have in the pics?