I just noticed that among a few posthumous obscurities recently uploaded to the Chopin page at IMSLP is one I've never seen before. In fact, its existence was unknown to me: it's a short mazurka in F-sharp, titled simply "Allegretto" and dedicated to Mlle Leopoldyna Blahetka.
Apparently this piece was not a recent discovery. I thought I was familiar with Chopin's entire oeuvre, but this
Allegretto completely escaped my attention. While not terribly significant—it's comparable in brevity and simplicity to the Largo in E-flat, the Cantabile in B-flat or the Album Leaf in E—it should be found interesting, especially to anyone who is as surprised by its existence as I was.
https://imslp.org/wiki/Allegretto_%28Chopin,_Frederic%29
Topic: Were you aware of this obscure mazurka (Allegretto) in F# by Chopin? I wasn't!