piano scale
G Locrian
G1A♭♭2B♭♭3C4D♭♭5E♭♭6F♭7
The only mode of the major scale whose fifth is diminished, which is why its tonic chord cannot rest.
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
GHA♭WB♭WCHD♭WE♭WFWG
What is true of it
G Locrian is G, A♭, B♭, C, D♭, E♭ and F, and back to G.
Its steps are H – W – W – H – W – W – W, where W is a whole step and H a half.
On the same tonic, G Phrygian differs from it by exactly one note.
Chords made only of these notes
Found by testing every chord in the catalogue against these 7 sounds, not chosen.