Looks like good Pedernales to me. Some call it Perd. It should be pretty good chipping as is, but if it is not cooked, it will get glossier with some heat, maybe 400 - 450 degrees F for a few hours. Beware that cooking whole rocks is risky. They tend to explode. If you knock it down into big flakes, they can be cooked with less danger of exploding. Try it raw first.
WA