Julia Wolfe descended hundreds of feet underground, into a dank, dark cavern with gleaming black walls: a Pennsylvania coal mine.

“You can’t believe people spent all day there,” Wolfe recalled Tuesday. “It was spooky, a little bit, but so fascinating, a strange kind of beauty.”

Wolfe’s visit helped inspire “Anthracite Fields,” a choral tribute to the state’s mining heritage – and, now, winner of the Pulitzer Prize in music. The judges described her work as a “powerful oratorio for chorus and sextet evoking Pennsylvania coal-mining life around the turn of the 20th Century.”

“I’m a little stunned,” Wolfe, a music professor at New York University, said a day after her win…