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
A-flat major major for G-sharp minor. (The same enharmonic situation occurs with the keys of D-flat major and C-sharp minor.) It was used quite often by Franz Schubert; twenty-four of Frédéric Chopin's piano pieces are in A-flat major, more than any other key. Beethoven chose A-flat major as the key of the slow movement for most of his C minor works, a practice which Anton Bruckner imitated in his first two C minor symphonies and also Antonín Dvořák in his only C minor symphony. Since A-flat major was not often chosen as the main key for orchestral works of the 18th century,