G-flat major Rondo-Finale of his Seventh Symphony. Mahler's Tenth Symphony was composed in the enharmonic key of F-sharp major. This key is more often found in piano music, as the use of all five black keys allows an easier conformity to the player's hands, despite the numerous flats. Austrian composer Franz Schubert chose this key for his third impromptu from his first collection of impromptus (1827). Polish composer Frédéric Chopin wrote two études in the key of G-flat major: Étude Op. 10, No. 5 "Black Key" and Étude Op. 25, No. 9 "Butterfly". French composer Claude Debussy used this key for one
Prelude in A-flat major (Rachmaninoff) 9–18, the section is restated though a transient modulation to E major (at measure 15). An imperfect cadence in the tonic bridges the transitory gap in measure 18 to the B section in E flat. Measures 19–20 introduce a variant of the main motive. Now in a new key, the bass melody changes, descending chromatically in an eighth-note figure. Measure 19 A transition section comes together though the combination of ascending and descending chromatic scale fragments at measures 31–41. Vertiginous modulations swing through E flat – G – C – F – A flat and B flat, before settling into