Diatonic scale are major scales (those with a major third/triad: Ionian, Lydian, and Mixolydian), three are minor (those with a minor third/triad: Dorian, Phrygian, and Aeolian). To these may be added the seventh diatonic scale, with a diminished fifth above the reference note, the Locrian scale. These could be transposed not only to include one flat in the signature (as described by Glarean), but to all twelve notes of the chromatic scale, resulting in a total of eighty-four diatonic scales. The modern musical keyboard originated as a diatonic keyboard with only white keys. The black keys were progressively added for several purposes:
Hexatonic scale Others have referred to it as the "Promethean chord". Since blue notes are alternate inflections, strictly speaking there can be no one blues scale, but the scale most commonly called "the blues scale" comprises a flatted seventh blue note, a flatted third blue note, and a flatted fifth blue note along with other pitches derived from the minor pentatonic scale: C E F G G B C. The tritone scale, C D E G G() B, is enharmonically equivalent to the Petrushka chord, C C E F G A. The "two-semitone tritone scale", C D D F G A, is