A natural minor scale
(or Aeolian mode scale)

Listen

A minor notes: A B C D E F G

3-notes chords built on A minor scale:

1. A Minor: A C E
2. B Diminished: B D F
3. C Major: C E G
4. D Minor: D F A
5. E Minor: E G B
6. F Major: F A C
7. G Major: G B D

4-notes chords built on A minor scale:

1. A Minor 7: A C E G
2. B Half Diminished 7: B D F A
3. C Major 7: C E G B
4. D Minor 7: D F A C
5. E Minor 7: E G B D
6. F Major 7: F A C E
7. G Dominant 7: G B D F