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I find that when I'm creating a chord progression from the harmonic minor scale that using all of its native chords sound weird. I'm specifically talking about the III augmented chord. Using III as a major chord sounds better, but it would seem that I'm borrowing from the natural minor scale. When I took Classical theory lessons I found that they only used the raised 7th in the V chord and in the vii dim chord. What are the rules for using certain chords in minor scales? There's also the melodic minor scale. Is this used for chord progressions at all?