Some of you guys who feed and run the dirtburners would probably know the answer.
Years ago when John Sutkus cleaned out the coal bunker in the Chama coal tipple he said the railroad did not want him to put the leftover coal in the current coal pile. They were telling him something to the effect that it wouldn't burn as hot as 'fresh coal', Marvin over on the other end of the railroad would only burn the coal we unloaded out of a drop bottom gon in the shop stove. Is there such thing as fresh and stale coal?