Chords in A Locrian

A Locrian is built from the notes A, Bb, C, D, Eb, F and G. Its scale carries 2 flats. Harmonising that scale in thirds gives seven chords — 3 majors, 3 minors and 1 diminished — starting on Adim as the iø. The chord on the fifth degree is Eb, a major bV, so A Locrian has the leading tone that makes a Eb-to-Adim cadence sound final.

Beyond those seven, A Locrian commonly borrows A (I), Bm (ii), C#m (iii), D (IV) and E (V) from the parallel major — the mixture chords that give a progression somewhere unexpected to go.