A previously unknown piece of music likely composed by a teenage Wolfgang Amadeus Mozart was recently uncovered at a library in Germany.

The piece, which dates to the mid- to late-1760s, consists of seven miniature movements for a string trio. It lasts around 12 minutes, researchers with the Leipzig Municipal Libraries said in a statement.

Researchers discovered the work at the city’s music library while compiling the latest edition of the so-called Koechel catalog, the definitive archive of Mozart’s musical works.

The piece is referred to as “Ganz kleine Nachtmusik” in the new Koechel catalog, according to the Leipzig libraries.

The Koechel catalog describes the piece as “preserved in a single source, in which the attribution of the author suggests that the work was written before Mozart’s first trip to Italy”, according to the municipal libraries.

The newly discovered manuscript, which consists of dark brown ink on medium-white handmade paper, was not penned by Mozart himself but is believed to be a copy made around 1780, the researchers said.

The young Mozart had been known to researchers up until now “mainly as a composer of piano music, arias and symphonies”, Ulrich Leisinger of the International Mozarteum Foundation in Salzburg said in a statement.

A list by Mozart’s father had alerted academics to the existence of “many other chamber music compositions” by the young artist, which were all thought to have been lost until the emergence of the string trio, Leisinger said.

“Since the inspiration for this apparently came from Mozart’s sister, it is tempting to imagine that she kept the work as a memento of her brother,” Leisinger said.

Born in 1756, Mozart was a child prodigy and began composing at a very early age under his father’s guidance.

The piece was performed by a string trio at the unveiling of the new Koechel catalog in the Austrian city of Salzburg on Thursday. It will receive its German premiere at the Leipzig Opera on Saturday.