The F locrian scale has 7 notes: F, Gb, Ab, Bb, B, Db and Eb. Its formula is 1 b2 b3 4 b5 b6 b7 and its steps, in tones, are ½ – 1 – 1 – ½ – 1 – 1 – 1.
The locrian mode is the most unstable mode: its diminished fifth takes away all stability. It is mostly used over the half-diminished chord.
F locrian
F Gb Ab Bb B Db Eb · 1 b2 b3 4 b5 b6 b7
Colored dots: notes of the scale, the root is the darkest.