At that insult, Harry had almost turned and shouted abuse back at her, but the coal was more important to him right now. It was being picked off the beach rapidly, and he was desperately scanning the ground. He had just spotted a piece of coal when she tapped him on the shoulder.

He rose. "Coal, of course, ye dumb cow. If ye're a housewife, ye'r husband must be a miserable sod." He took a few steps to where he had seen a piece of coal and picked it up, shoving a child out the way who had been trying to get there first. He turned back to the young woman. "If it burns... it's coal. If not... it's a rock."