Wiktionary
steam coal
n. A coal which has a grade between bituminous coal and anthracite, and which was once widely used as a fuel for steam locomotives.
WordNet
steam coal
n. coal suitable for use under steam boilers
Usage examples of "steam coal".
Luckily, you have excellent steam coal here in Hayapalco, I'm told, so we'll just unload what's left of ours and take on all that we need from the government stores.
They'd get their coal there from Norfolk, Virginia, or else Welsh steam coal from Cardiff or Newport.