Minor Scales and Keys

David Loberg Code, Western Michigan University

Minor scales come in three variants: natural, harmonic, and melodic.  It is probably easiest to compare them with the major scale.

                           1       2       3       4       5       6       7       8

D major               D      E       F#     G       A       B       C#     D

D natural minor     D      E       F       G       A      Bb       C       D

D harmonic minor    D      E       F       G       A      Bb      C#     D

D melodic minor    D      E       F       G       A       B       C#     D   (descend with natural minor C     Bb  A  etc.)

To form the natural minor scale, we can lower scale degrees 3, 6, and 7.  This will change these intervals to a minor 3^rd, minor 6^th, and minor 7^th.  (That is why this is called a minor scale.) 

The harmonic minor scale uses the same leading tone as the major scale (C#), but a minor 3^rd and 6^th.  The melodic minor scale is more unusual because it is different going up then it is going down.  Notice how the 6^th and 7^th scales degrees change from B and C# to Bb and C natural.  Going up, melodic minor is almost the same as major, except for the minor 3^rd.  Going down it is exactly the same as minor.

Minor key signatures are formed from the natural minor form of the scale.  Therefore, the key signature for D minor has only one flat: Bb.  If a piece is using the harmonic or melodic forms of the minor scale, the "extra" accidentals are NOT included in the key signature.  They are written in separately each time they are needed in the music.  It may seem silly, but that is how it is done.   As a result, the order of sharps and flats in minor key signatures is the actually the same as for major keys.

To determine the name of a minor key from the key signature, first find the major key using the tricks for sharps or flats described earlier.  Once you know the major key, go to the 6^th scale degree.  This is the starting note for the relative minor, that is the minor key with the same key signature.  For example:

                  The key signature has 3 sharps (F#-C#-G#).

                  The last sharp is G#, a  minor 2^nd above that is A.

The major key is A major.  The 6^th scale degree of
A major is F#.  The minor key is F# minor.

WARNING: When looking at a piece of music, do not automatically assume that it is in a major key.  The key signature could be for either major or minor.  You need to look for additional clues to determine which one is correct.  What note does the piece start on or end on?  Often, but not always, this will be the tonic (Do).  Are there any "extra" accidentals?  Remember, harmonic and melodic minor will have extra accidentals which are not included in the key signature.