First Mozart comes back with a banger, and now so has Frédéric Chopin. A previously unknown waltz by the great Polish pianist and composer has been discovered in a library in New York, leading to an outpouring of excitement across the classical music community.

According to the New York Times, Robinson McClellan was cataloging cultural memorabilia in the vault of the Morgan Library and Museum in Manhattan when he found a pockmarked manuscript signed by Chopin.

He showed a photo of his discovery with Jeffrey Kallberg, a leading Chopin scholar at the University of Pennsylvania. “My jaw dropped,” Kallberg said. “I knew I had never seen this before.”

After a comprehensive analysis, experts concluded that the work is indeed an unknown waltz by Chopin. The momentous find is dated between 1830 and 1835, when Chopin was in his early 20s, and the music strays from the composer’s usual style.

The work is notably shorter than Chopin’s other waltzes – only 48 measures long with a repeat, or about 80 seconds. The piece, in A minor, also has unusually dynamic markings, including a triple forte, signifying maximum volume, near the start.

Renowned pianist Lang Lang recently recorded the waltz for the New York Times at Steinway Hall in Manhattan. “This is not the most complicated music by Chopin,” he told the publication, “but it is one of the most authentic Chopin styles that you can imagine.” Watch the performance here.