Augmented

Two triads, interlocked

Take C E G♯ and the triad a half step below it, B D♯ G, and play the six notes together. That is the whole scale. The construction explains the step pattern: from each note of one triad it is a half step to the nearest note of the other, and a minor third onwards to the next.

This is why the scale is sometimes called the augmented hexatonic, and why it is often taught as a pair of shapes rather than a run of six notes. Thinking of it as two triads makes it playable immediately; thinking of it as a scale makes it hard to phrase.

Three majors and three minors — the same count as the major scale

The augmented scale parts company with its symmetrical neighbours exactly here. Our harmonic analysis returns a family formula of 3×3: three major triads (C, E, A♭) and three minor triads (Cm, Em, A♭m), the identical count found in an ordinary major scale. It also contains six augmented triads and, notably, not a single diminished one.

Because those triads exist, functions exist too. Read from C the analysis assigns C as tonic, E as subdominant and A♭ as dominant, with a parallel minor system on the same three roots. A symmetrical scale that nonetheless supports a full tonic–subdominant–dominant reading is rare, and it is the reason this scale can carry a passage on its own where the whole tone scale cannot.

Four transpositions, not twelve

Moving the scale up a minor third returns the same six notes, so the twelve starting pitches reduce to four distinct collections. That is more variety than the whole tone scale offers and far less than an ordinary seven-note scale, which places the augmented scale in a useful middle ground: familiar enough to be memorised, symmetrical enough to modulate by surprise.

The symmetry has a practical consequence. Any figure you learn can be moved up or down a major third and lands back inside the same collection, so one idea covers three keys. Guitarists exploit this directly, since a major third is a fixed four-fret shift on every string pair except one.

Coltrane, and modulation by major third

The best known use of major-third symmetry in jazz is the cycle behind «Giant Steps», where the tonal centre moves by major thirds instead of fifths. The augmented scale sits naturally on that cycle, since its own structure repeats at exactly that interval, and players use it to connect keys that classical harmony treats as distant.

In nineteenth-century music the same relationship appears as a colour rather than a system — Liszt and Rimsky-Korsakov both move by major thirds for effect. The scale gives a modern player a single collection that covers all three centres at once, which is a genuinely different way to think about a chord change.

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