• Every major and minor scale has seven special triads, called diatonic triads, which are formed from that scale's notes.
• To discover the diatonic triads, a three step process must be used.
• First, construct the scale. We will be using the C major scale for our first example.
• Next, stack two generic thirds on top of each note.
• Finally, analyze the resulting triads.
• The first triad is C--E--G, a major third and a perfect fifth. Therefore, the triad is major.
• The second triad is D--F--A, a minor third and a perfect fifth. Therefore, it is minor.
• The third triad is E--G--B, a minor third and a perfect fifth. Therefore, it is also minor.
• The fourth triad is F--A--C, a major third and a perfect fifth. Therefore, it is major.
• The fifth triad is G--B--D, a major third and a perfect fifth. Therefore, it is also major.
• The sixth triad is A--C--E, a minor third and a perfect fifth. Therefore, it is minor.
• The seventh triad is B--D--F, a minor third and a diminished fifth. Therefore, it is diminished.
• The eighth triad is a repetition of the first (C--E--G), making it major.
• The first triad of a major scale will always be major, the second and third triads will always be minor, etc.
• Next, we will uncover the diatonic triads of the C Natural Minor scale.
• First, the scale is constructed. Notice that we are using a key signature rather than placing the accidentals by each note.
• Again, stack two generic thirds.
• Finally, let's analyze the resulting triads.
• The first triad is C--Eb--G, a minor third and a perfect fifth. Therefore, the triad is minor.
• The second triad is D--F--Ab, a minor third and a diminished fifth. Therefore, it is diminished.
• The third triad is Eb--G--Bb, a major third and a perfect fifth. Therefore, it is major.
• The fourth triad is F--Ab--C, a minor third and a perfect fifth. Therefore, it is minor.
• The fifth triad is G--Bb--D, a minor third and a perfect fifth. Therefore, it is also minor.
• The sixth triad is Ab--C--Eb, a major third and a perfect fifth. Therefore, it is major.
• The seventh triad is Bb--D--F, a major third and a perfect fifth. Therefore, it is also major.
• The eighth triad is a repetition of the first (C--Eb--G), making it minor.
• Next, we will discuss the diatonic triads of harmonic minor.
• To convert natural minor to harmonic minor, the seventh tone is raised a half step. Therefore, each Bb (the seventh tone of C minor) is raised to a B.
• Since the third, fifth, and seventh chords have been altered, they need to be reanalyzed.
• The third triad is now Eb--G--B, a major third and an augmented fifth. Therefore, it is augmented.
• The fifth triad is now G--B--D, a major third and a perfect fifth. Therefore, it is major.
• The seventh triad is now B--D--F, a minor third and a diminished fifth. Therefore, it is diminished.
• Finally, we will discuss the diatonic triads of melodic minor.
• To convert harmonic minor to melodic minor, the sixth tone is raised a half step. Therefore, each Ab (the sixth tone of C minor) is raised to an A.
• Since the second, fourth, and sixth chords have been altered, they need to be reanalyzed.
• The second triad is now D--F--A, a minor third and an perfect fifth. Therefore, it is minor.
• The fourth triad is now F--A--C, a major third and a perfect fifth. Therefore, it is major.
• The sixth triad is now A--C--Eb, a minor third and a diminished fifth. Therefore, it is diminished.
• Use this chart to reference the diatonic triads in each scale.