15.22Chromatic mediants

Now a related but broader concept.

Two chords are chromatic mediants if their roots are a third apart and they share the same chord quality or have chromatic note relationships.

Examples from C:

C major → E major

roots a major third apart.

E major is:

E G♯ B

It is not diatonic to C major.

Or:

C major → A♭ major

roots a major third apart downward.

These relationships are common in film music and Romantic harmony.