Aeolian (Natural Minor)

The notes

G A B♭ C D E♭ F, then G. Two flats, the same two as B♭ major. The B♭ is the minor third that defines the scale; the E♭ is the sixth, and it is what separates natural minor from the dorian mode, which is otherwise identical.

Raise the F to F♯ and you have the harmonic minor, with its augmented second between E♭ and F♯ — the interval that gives so much klezmer and flamenco writing its character.

On the fretboard

From the third fret with the root on the low E string, the movable minor shape covers two octaves without an open string. That portability is the compensation for the lack of open notes.

The chords are Gm, A diminished, B♭, Cm, Dm, E♭, F. Four of the seven require barres, and the tonic is one of them.

Where it is used

Jazz, big band and orchestral writing. It is also common in film scoring, where the flat keys are preferred because strings and brass sit well in them.

Guitar music reaches G minor mostly through the parallel switch from G major, which is a natural guitar key — the same root, three notes changed, and a very different weight.

The practical route for a guitarist is a capo at the third fret with E minor shapes, which produces G minor with open-string resonance the barre version cannot give. Most recordings in this key were made that way.