No heat. That rock came from Craig Ratzat. Some of it had water that came to the surface when I broke up the nodules, but of course I knapped that one out much later and made gun flints with the rest...or more accurately, tried to produce blades to make gun flints. I think I waxed the point with floor wax. There were two grades; this one and one with gray spots in it. A few nodules had horrible inclusions. It's a nice material. Flint is of course dark colored chert in reality, but not a chalcedony like agate, jasper and other materials. It is not terribly shiny by nature, the wax did that.