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
D-flat major Mahler concluded his last completed Ninth Symphony with an adagio in D-flat major, rather than the home key of D major of the first movement. Anton Bruckner wrote the third movement of his Symphony No. 8 in D-flat major, while every other movement is in C minor. Antonín Dvořák wrote the second movement of his Symphony No. 9 in D-flat major, while every other movement is in E minor. The first piano concerto of Sergei Prokofiev is also written in D-flat major, with a short slow movement in G-sharp minor. Aram Khachaturian wrote his Piano Concerto, Op. 38, in the