Clothing coal. But long before that time! Eastern Pennsylvania was comparatively populous, and sturdy farmers filled the lands in the valleys of the Schuylkill and the Wyoming. The farm lands were not of the best, and there were many outcropping of a hard, black rock that interfered with their plowing.
It was just before the Revolution, that a hunter was lost one night on a chilly mountainside near the Schuylkill, he built a fire beneath a stump and dozed off. When he awoke in the morning, he found that the stump had burned away, but, to his surprise, the broken lead pipe of black rock just above it had been transformed into a glowing bed of coals. The rock, in fact, had caught fire and was burning.
The hunter carried the story of the burning rock to Obadiah Core, a blacksmith of Wilkes-Barre, and Obadiah put some of the black rock of his pasture into his forge and it burned. It was half a generation later that Judge Jesse Fells, of Wilkes-Barre, used this black rock as fuel in the manufacture of nails. It was another half a generation later that local enthusiasts floated two barges of this rock coal down to Philadelphia and offered it for sale. It was tried by several householders without success and finally broken up and used for graveling garden walks. 