yea i'd say its coastal too... i would not use a sludge hammer if you can help it.. A sludge hammer will cone it up bad.
I don't know about all this slow cooking stuff billy.. i have cooked allot of rock and for the most part i never exceed the max timp but i cook it fast.. I'll set the oven to 250* let it sit for 1hr then ramp it up 50* an hr let it set at max timp for 5-8 hrs then i just tern it off.. I've cooked coastal , coral , horse creek, TX flint , Kay co. , alabats , and some others like this with no problems.