Hexatonic
A hexatonic scale is a scale with 6 tones per equave.
Hexatonic MOS scales may be found at: Hexatonic MOS.
Other hexatonic scales may be found at: Category:6-tone scales.
Hexatonic scales may sometimes be used as chords rather than scales, in which case they are called hexads.
“Equihexatonic” scales are scales with 6 roughly equally spaced tones per octave. Equihexatonic scales are rare in the world’s musical traditions, with one big exception: the whole tone scale of modern Western music. It is an equihexatonic scale, so equi-, in fact, that it is exactly 6edo.
6 equal frequency divisions instead of pitch gives the hexatonic overtone scale, the first mode of 6afdo.
Although equihexatonic scales may be rare, unequal hexatonic scales occur fairly commonly in the world’s musical traditions, especially in the folk music of some parts of Europe.
Folk music of Scotland and Ireland often uses a 6-tone scale which can be arrived at by stacking perfect fifths with an octave period, which depending on the mode used may be called the “Scottish hexatonic” scale, the “hexatonic minor” scale or other names. Historically, the tuning varied, though today it is usually (but not always) tuned to 12edo.
The folk music of some parts of Croatia often uses a 6-tone just intonation scale called the Istrian scale. It uses an unequal tuning, best approximated as a 6-tone subset of 7ifdo (subharmonics 7 to 14).