In music and music theory, a hexatonic scale is a scale with six pitches or notes per octave. Famous examples include the whole tone scale, C D E F♯ G♯ A♯ C; the augmentedscale, C D♯ E G A♭ B C; the Prometheus scale, C D E F♯ A B♭ C; and what some jazz theorists call the “blues scale”, C E♭ F G♭ G B♭ C.
Whole tone scale
This whole-tone scale has appeared occasionally and sporadically in jazz at least since Bix Beiderbecke’s impressionistic piano piece In a Mist. Bop pianist Thelonious Monk often interpolated whole-tone scale flourishes into his improvisations and compositions.
It made one of its most celebrated early appearances in Franz Liszt’s Faust Symphony (Eine Faust Symphonie). Another famous use of the augmented scale (in jazz) is in Oliver Nelson’s solo on “Stolen Moments”. It is also prevalent in 20th century compositions by Alberto Ginastera, Almeida Prado, Béla Bartók, Milton Babbitt, and Arnold Schoenberg, by saxophonists John Coltrane and Oliver Nelson in the late 50s and early 60s, and bandleader Michael Brecker. Alternating E major and C minor triads form the augmented scale in the opening bars of the Finale in Shostakovich’s Second Piano Trio.
The Prometheus scale is so called because of its prominent use in Alexander Scriabin’s symphonic poem Prometheus: The Poem of Fire. Scriabin himself called this set of pitches, voiced as the simultaneity (in ascending order) C F♯ B♭ E A D the “mystic chord”. Others have referred to it as the “Promethean chord”.
Since blue notes are alternate inflections, strictly speaking there can be no one blues scale, but the scale most commonly called “the blues scale” comprises a flatted seventh blue note, a flatted third blue note, and a flatted fifth blue note along with other pitches derived from the minor pentatonic scale: C E♭ F F♯ G B♭ C
The tritone scale, C D♭ E G♭ G(♮) B♭, is enharmonically equivalent to the Petrushka chord, C C♯ E F♯ G A♯.
The two-semitone tritone scale, C D♭ D F♯ G A♭, is a symmetric scale consisting of a repeated pattern of two semitones followed by a major third now used for improvisation and may substitute for any mode of the jazz minor scale. The scale originated in Nicolas Slonimsky’s book Thesaurus of Scales and Melodic Patterns through the, “equal division of one octave into two parts,” creating a tritone, and the, “interpolation of two notes,” adding two consequent semitones after the two resulting notes.