Would lunar power stop it from running out as quick? You could probably control the flow of the heat easier too, stop it from overheating. [ But then he clicks his tongue, adds with a sheepish tilt of his head as he holds it back out, turned off. ] --but I don't know anything about stones.

[ He could be full of shit, really. It's more of a curiosity than a suggestion, since the guy's probably thought about it. Did it even make a difference? This isn't exactly Earth tech, and he wonders if it's even a problem, the heat of a stone if managed properly -- with either the right wires, or spells.]