The Chromatic Mediant
Chromatic mediants are chords whose roots lie a third apart but whose notes do not all belong to one diatonic key. In C major, A-flat major and E major provide two clear examples.
- roots a third apart
- chromatic chord tones
- often the same chord quality
same family
The progression
- I
- bVI
- I
- III
Identify the relationship
C major contains C-E-G.
A-flat major contains A-flat-C-E-flat. Its root is a major third below C, and C is the shared pitch.
E major contains E-G-sharp-B. Its root is a major third above C, and E is the shared pitch.
Both new chords contain notes outside C major. The root distance connects them to the tonic, while the chromatic notes create the change of colour.
Chromatic versus diatonic mediants
The diatonic mediant in C major is Em, built on scale degree 3. C and Em share E and G and belong to the same key.
E major is a chromatic mediant because G becomes G-sharp. A-flat major is also chromatic in C major; it can additionally be understood as a chord borrowed from C minor.
These labels describe relationships from different angles. "Chromatic mediant" focuses on root distance and chord quality. "Modal interchange" focuses on borrowing from a parallel mode.
Make the voice leading audible
| Move | Common tone | Chromatic motions |
|---|---|---|
| C to A-flat | C | E to E-flat, G to A-flat |
| C to E | E | G to G-sharp, C to B |
Keep the common tone in the same voice. Let the other two notes move by semitone or whole tone. The change becomes connected and surprising at once.
Use one pair as a colour
- Establish C majorplay C long enough that it feels central.
- Introduce A-flat or Ekeep the shared tone on top.
- Return to Chear whether the chromatic chord acted as contrast or suggested a new key.
- Add a melodytarget the altered note so the harmonic colour becomes part of the tune.
Make it yours
- Change register
Wide orchestral spacing makes the move broad; close keyboard voicing makes the semitone lines more exposed.
- Sequence the idea
Repeat a major-third root relationship to move rapidly through distant key areas.
- Use it at a formal change
A chromatic mediant can mark a new section because its colour differs immediately from the diatonic surroundings.
When it is useful
Use chromatic mediants when a diatonic progression needs one clear expansion of colour. They are common in film, game and Romantic harmony, but the technique also works in concise pop writing.