Notes: C, D, E, F, G, A, and Bb - Key: C - Origin: Church - Category: Octatonic Scales
The C Gregorian no.7 uses eight notes per octave. Because of this same reason it is a member of the so called Octatonic -scales that have Eight-note (or Eight-tone). On the piano keyboard, it is made up of one black keys: Bb and six white keys: C, D, E, F, G, and A. This combination makes this scale - as well as the C Gregorian no.1, C Gregorian no.2, and C Gregorian no.3 - as great choices for composing or improvising Church music.
If we take a look a the key signature of the C Gregorian no.7 Scale we can find it has one flats and no sharps. Therefore, on sheet music you will find one accidentals on the score. The notes of this scale are: C, D, E, F, G, A, and Bb.