Aeolian , the 6th mode.
Aeolian can also be refered to as the natural minor scale.
It's called the sixth mode because it starts on the sixth note of the major scale.
Here is how this minor scale looks based on the tone, semi-tone method.
The scale has a natural fingering that is easy to learn when played in two octaves.
Don't understand the fingering chart? Go to the bass guitar scales intro.
You can hear this scale used primarily in classical music like in my lesson on a Bach fugue.
If you are a song writer and you want to make the music sound more "dark" using a minor key, and melody notes from the the natural minor scale is the way to go.
I have also heard the natural minor scale used in heavy metal music from bands like Metalica, Black Sabbath, and Megadeath.