Ionian #5
This scale is also known by other names: Ionian Augmented.
2 - 2 - 1 - 3 - 1 - 2 - 1About Ionian #5
Ionian ♯5 is 1 2 3 4 ♯5 6 7 — the third mode of harmonic minor, also called Ionian augmented. In C it gives C D E F G♯ A B: the major scale with its fifth degree raised, which turns the tonic triad into an augmented chord.
A major scale that cannot rest
Every other major-sounding scale has a perfect fifth above the root, and that interval is what makes a tonic feel stable. Raise it and the stability goes: the triad built on the root becomes augmented, a chord with no perfect fifth at all and therefore no natural resting point.
This is what the scale is for. It supplies the notes over an augmented major seventh chord — Cmaj7♯5 — which appears as a passing sonority in jazz ballads and in film harmony, usually while an inner voice climbs from the fifth to the sixth.
The scale is the third mode of harmonic minor, so in practice it shares its notes with A harmonic minor. A player who knows the parent already has every note; what is new is treating C as home while the fifth above it is sharp.
Where the augmented second lands here
Harmonic minor's three-semitone gap sits between the fifth and sixth degrees in this rotation — G♯ to A in C Ionian ♯5 is only a semitone, while F to G♯ is the augmented second. Placed between the fourth and fifth degrees, it lands in the middle of the scale rather than at either end.
That position is comparatively easy to use. Melodies can move around the gap without crossing it, so the scale sounds like a major scale with an unusual fifth rather than like an exotic quotation — which is why it survives in jazz writing where the more strident modes do not.
It also means the scale works better as harmony than as melody: the interesting event is the chord, not the line.
How it is actually used
The typical appearance is one bar long. A major seventh chord is followed by the same chord with a raised fifth, then by something else — the ♯5 acting as a chromatic step from the fifth toward the sixth. Ionian ♯5 is the scale for that single bar.
Search demand reflects this: a few dozen queries a month, mostly from players analysing a chord they met rather than from anyone seeking a new scale to practise. That is an accurate picture of an inner mode, and pretending otherwise would not help anyone.
For guitarists there is no new shape to learn. Play the harmonic minor pattern a major third below and treat the third degree as the root; the fingering is one you already own.
Frequently asked questions
What is the Ionian ♯5 scale?
The third mode of harmonic minor, spelled 1 2 3 4 ♯5 6 7 and also called Ionian augmented. In C that is C D E F G♯ A B — the major scale with a raised fifth, which makes the tonic triad augmented.
What chord does it fit?
An augmented major seventh — Cmaj7♯5. That chord usually appears as a single passing bar, with the raised fifth acting as a chromatic step between the fifth and the sixth, and this scale supplies the notes while it sounds.
Is it worth learning as a separate scale?
For most players, no. It shares every note with the parent harmonic minor a major third below, so the fingering is already familiar. The name is worth knowing for analysis — to say what a bar was doing — rather than as a new pattern to practise.
Related Scales from Harmonic Minor
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