This Micro Lesson works through a, "Key of E Minor," riff that could be used within any form of Classic-Rock, Hard-Rock or Heavy Metal styles of music.
The riff is performed without distortion, (and you should play it clean for awhile until you properly learn it). But, as soon as this riff is committed to memory, be sure to add your favorite tube over-drive, or any additional distortion pedals to create just the right Rock /Metal sound.
The low 'Open "E" 6th String' starts the riff off and progresses through scale tones from the notes built around both the, "E Natural Minor and the E Minor Pentatonic," scale patterns. In measure two, there's even a, "C maj7" arpeggio off of the 5th guitar string.
The third measure uses opposing intervals compared to measure one to create a more expanded sound. A composing technique often used in Rock and Metal riffs. Watch measure four, there's a fast pace 16th-note triplet, (hammer-on /pull-off) phrase, which operates to turn the entire idea around.
Take your time and be sure to memorize the riff for best results when the distortion is cranked up. Be sure to try a few different types of Palm-Muting and some Right-hand Percussive technique to really bring up that, "Metal Sound." Enjoy!
Micro Lesson 226: "E Minor" Rock /Metal Riff