piano scale
A Phrygian
A1B♭♭2C♭3D4E5F♭6G♭7
Minor with a flattened second — the half step right above the tonic is the whole character.
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
AHB♭WCWDWEHFWGWA
What is true of it
A Phrygian is A, B♭, C, D, E, F and G, and back to A.
Its steps are H – W – W – W – H – W – W, where W is a whole step and H a half.
On the same tonic, A natural minor differs from it by exactly one note.
Chords made only of these notes
CmajorC7dominant seventhDmminorDm7minor seventhEdimdiminishedEm7♭5half-diminished seventhFmajorFmaj7major seventh
Found by testing every chord in the catalogue against these 7 sounds, not chosen.