piano scale
B♭ Locrian
B♭1C♭♭2D♭♭3E♭4F♭♭5G♭♭6A♭♭7
The only mode of the major scale whose fifth is diminished, which is why its tonic chord cannot rest.
The same sounds spelled from the other side are A♯ Locrian.
Written out
Every accidental is written in, rather than left to a key signature, so the letters can be read one at a time.
The step pattern
B♭HC♭WD♭WE♭HF♭WG♭WA♭WB♭
What is true of it
B♭ Locrian is B♭, C♭, D♭, E♭, F♭, G♭ and A♭, and back to B♭.
Its steps are H – W – W – H – W – W – W, where W is a whole step and H a half.
It costs 7 alterations to write — near the limit of what a key signature can carry.
On the same tonic, B♭ Phrygian differs from it by exactly one note.
Chords made only of these notes
D♭mminorD♭m7minor seventhE♭mminorE♭m7minor seventhG♭majorG♭7dominant seventhA♭mminorA♭m7minor seventh
Found by testing every chord in the catalogue against these 7 sounds, not chosen.