Harmonic Minor Scale
The harmonic minor is very similar to the natural minor scale, except for the fact that the seventh tone is raised half a step. A natural minor looks like this: A B C D E F G and back to A. The harmonic minor scale is A B C D E F G# and then back to A. As you can see there is one and a half steps from F to G#.
The harmonic minor scale is often used in classical, metal, and neoclassic shred
Harmonic Minor Scale in the Key of A