Freshly baked coal thread, with the coal baked up in mother earth under extreme pressure and heat for tens to hundreds of millions of years. In fact, heat is a much more important factor in the coalification process than time is.
There can be bituminous rank coals that are tens of millions of years old and mere lignite coals that are hundreds of millions of years old due to differences in underground heat.

This thread is dedicated to the amazing Illinois Coal Basin: all bituminous, Carboniferous (specifically Pennsylvanian) in age, and energy dense albeit high in sulfur, which is readily mediated by scrubbers in coal-fired power plants.
Illinois coal is weathering America's coal production downturn remarkably well thanks to foreign markets, like in Asia and South America, wanting it. Coal is easily shipped via Mississippi River coal barges down to the Gulf of Mexico (or is it the Gulf of America now?) for transfer to oceangoing coal barges.