FamousMystic chordPrometheus: The Poem of Fire, Op. 60, 1911 · Alexander Scriabin
The opening, bars 1–12: a broadly spaced, quiet chord in the winds and tremolo strings over a soft bass-drum and timpani roll. It is the 'mystic chord on A' (A, D♯, G, C♯, F♯, B), sounded with a note other than A in the bass. The work is built from transpositions of this chord.
A six-note chord built mostly in fourths, here A, D♯, G, C♯, F♯ and B, the quiet, hovering sound that opens Scriabin's Prometheus: The Poem of Fire. It has no clear home key, and Scriabin built the whole work from it, moving it to other pitches instead of resolving it. Written on one note it reads as a thirteenth chord with a sharp eleventh.
Also called mystic, Prometheus chord, Chord of the pleroma, Synthetic harmony, chord of Prometheus (Sabaneyev), chord of the pleroma (Bèlza)
Sources: Royal S. Brown, program note on Prométhée (American Symphony Orchestra, first in Fanfare) · Tyler Secor, 'Mystic Chord Harmonic and Light Transformations in Alexander Scriabin's Prometheus' (MM thesis, University of Oregon, 2013) · Anna Gawboy and Justin Townsend, 'Scriabin and the Possible', Music Theory Online 18.2 (2012) · Mystic chord (Wikipedia)