Prometheus Scale

The Prometheus scale comes from Alexander Scriabin's 1910 orchestral work "Prometheus: The Poem of Fire," where it serves as the harmonic foundation. Scriabin was obsessed with developing a new harmonic language independent of traditional major/minor tonality, and the Prometheus scale (also called the "mystic chord" when voiced as a stack of intervals) was central to his mature style. It has a floating, ambiguous quality that anticipates both impressionism and jazz harmony.

Construction

C Prometheus scale:
C  D  E  F#  A  B♭  C

Formula: 1  2  3  #4  6  ♭7

Step pattern: W - W - W - m3 - H - A2

Six notes (hexatonic).

The scale omits the 5th — unusual for a Western scale and part of what gives it its floating quality. The #4 (tritone) and ♭7 create the dominant/Lydian flavour; the natural 6th and absence of a 5th create the ambiguity.

The Mystic Chord

Scriabin's "mystic chord" stacks the Prometheus scale notes in fourths rather than thirds:

C — F# — B♭ — E — A — D
(stacked in fourths from the tritone up)

This is C, F#/G♭, B♭, E, A, D — the same six notes as C Prometheus.
Voiced on piano this creates a dense, shimmering cluster of superimposed fourths.

The mystic chord is the harmonic signature of Scriabin's late works. It hovers between being a dominant seventh chord with extensions (it contains the tritone F# and the ♭7) and something else entirely — the absence of a perfect fifth means it doesn't resolve normally.

Relation to Other Scales

C Lydian dominant: C D E F# G A B♭   (7 notes)
C Prometheus:      C D E F#   A B♭   (6 notes — omits the 5th)

The Prometheus scale is the Lydian dominant without the 5th.

This connection to Lydian dominant means the Prometheus scale has application over the same chords — unresolved dominant seventh chords, tritone substitutions, floating modal harmonies. Some jazz musicians have drawn on it for its impressionistic quality, particularly in atmospheric ballad playing.