Chords in F Aeolian

F Aeolian is built from the notes F, G, Ab, Bb, C, Db and Eb. Its scale carries 4 flats. Harmonising that scale in thirds gives seven chords — 3 majors, 3 minors and 1 diminished — starting on Fm as the i. The chord on the fifth degree is Cm rather than a major V, so F Aeolian has no leading tone and resolves by step and colour instead of by dominant pull — the sound that separates it from a plain F major.

Beyond those seven, F Aeolian commonly borrows F (I), Gm (ii), Am (iii), Bb (IV) and C (V) from the parallel major — the mixture chords that give a progression somewhere unexpected to go.