Question on the formation of the Harmonic field in general

Question

Given a key note, you can build up any sort of scale, for scales are just patterns of whole and half steps. The minor and major are examples.

Now, if the scale is the set of notes, the harmonic field is the set of chords.

So, suppose we want to write a music in the C key. The next natural step is to search chords. Well, here I became confused; I will explain:

It seems that the "harmonic field construction" is formed, every time, just with the major scale! Example:

1. key: c
2. major scale: c d e f g a b
3. Harmonic field: C Dm Em F G Am Bdim

My question is:

How to build the harmonic field in general?

Note that, I know how to pick a key note, and I know how to establish a scale pattern and write the scale for a given key note. But, the harmonic field in 3) is very specific, the II, III and VI degrees are minor chords, the I, IV and V are major chords and the last degree is diminished. So, I suspect that if I write the minor scale in 2) the harmonic field will not follow the rules of 3).

Answer 1

Here’s how you build a harmonic field from a heptatonic or octatonic scale:

1. Start with the first note of the scale and use it as the root of the first chord in the harmonic field.
2. To determine the second note of a chord in the harmonic field, go up the scale two notes from the root note of the chord. For the first chord, this will be the third note of the scale.
3. To find the third note of a chord in the harmonic field, go up the scale two notes beyond the second note of the chord, or four notes from the root of the chord. For the first chord, this will be the fifth note of the scale.
4. You have now formed the first chord (triad) in the harmonic field. Determine its quality (e.g., major, minor, augmented, diminished, etc.) and make a note of it.
5. Repeat steps 2-4 based on each note of the scale to determine the triads that make up the harmonic field for the scale.

For example, the harmonic field of the harmonic minor scale, is as follows (using A harmonic minor as the example scale):

• A minor (i)
• B diminished (ii°)
• C augmented (III+)
• D minor (iv)
• E major (V)
• F major (VI)
• G# diminished (vii°)

Note: A harmonic minor is A - B - C - D - E - F - G#

Answer 2

The question supposes that all music is diatonic - using only the notes from the particular scale involved. As in key C, only notes CDEFGAB are available for playing. That seems to be a common misconception reading quite a few questions posed on this site alone. It's nowhere near reality, but let's go with it for now.

True, only using diatonic notes, and tertian harmony (stacks of thirds), we do indeed end up with M m m M M m d as the 7 available chords. Quartal harmony gives different chords.

But, you ask about minor. By stacking thirds, you will get a set of chords. More than you do with major, due to there being harmonic and melodic minr scales, giving more triad and four note chords.