Necho Allen was a Pennsylvanian who is sometimes credited with discovering anthracite coal in Pottsville, Pennsylvania in 1790. His campfire accidentally ignited some of it while he was on a hunting trip.
There were earler reports of coal in the vicinity. 
Anthracite became economically valuable later on because it burns cleaner than bituminous coal. Pennsylvania's large anthracite deposits are close to Philadelphia, Baltimore, and New York.