So what happens if we want to harmonize the (harmonic) minor scale? Lets have a look (the harmonic minor scale is the basis for harmonies in a minor key). As an example we will use the A harmonic minor scale:
The first chord in this scale is (obviously) A minor, made up of the 1st (A), the 3rd (C) and the 5th (E) notes of this scale. If we extend this to a 7th chord we get A minor/major 7, since the 7th is a major (sharp) 7th (see ‘Four Part Harmonies’).
- The 2nd chord (B) contains the 2nd (B), 4th (D) and 6th (F) notes. This turns out to be a diminished triad, B minorb5, since the 3rd note (D) is a minor third and the 5th note (F) is flattened.
- The 3rd chord (C) contains the 3rd (C), 5th (E) and 7th (G#) notes. We see that it is an augmented triad, since the 5th (G#) is sharpened. So we end up with C aug (also denoted as C+). This chord is rarely used in minor harmonies because of it’s unusual sound.
- The 4th chord (D) will contain the 4th (D), 6th (F) and 1st (A) notes of the scale. This is a minor triad, so we get D minor.
- The 5th chord (E) will be composed of the 5th (E), 7th (G#) and 2nd (B) notes. This is a major triad, so we end up with E major.
- The 6th chord (F) contains the 6th (F), 1st (A), and 3rd (C) notes. This contains a major third so we get F major.
- The 7th chord (G#) contains the 7th (G#), 2nd (B) and 4th (D) notes. This is a diminished triad (minor third and flat 5th), so we get G#minorb5.
These chords are the same across all (harmonic) minor keys. So, in any (harmonic) minor key, we get the following chords:
The chord built on the 1st note of the scale is MINOR
The chord built on the 2nd note of the scale is DIMINISHED (minorb5)
The chord built on the 3rd note of the scale is AUGMENTED (relative major)
The chord built on the 4th note of the scale is MINOR
The chord built on the 5th note of the scale is MAJOR (dominant)
The chord built on the 6th note of the scale is MAJOR
The chord built on the 7th note of the scale is DIMINISHED (minorb5)
You will notice this produces quite a few ‘non-standard’ (augmented and diminished) chords. For this reason, songs in a minor key will not only take chords from the harmonized harmonic minor scale, but also from the harmonized melodic minor and harmonized natural minor scales as well.
As an exercise, write out the melodic minor and natural minor scales, and harmonize these in the same way. You will find a different group of chords to use in addition to the above. This gives us a wide variety of chords to use when playing in a minor key.