The Magic Chord is a chord and installation (1984) created by La Monte Young, consisting of the pitches E, F, A, B♭, D, E, G, and A, in ascending order and used in works including his The Well-Tuned Piano and Chronos Kristalla (1990). The latter was performed by the Kronos Quartet and features all notes of the magic chord as harmonics on open strings. The quartet has been described as, "offer[ing] perhaps the ultimate challenge in performing in a just environment". The Well-Tuned Piano is based on a pitch lattice of perfect fifths and harmonic sevenths, tuned as follows: