From wikipedia: https://en.wikipedia.org/wiki/Heavy_metal_music#Typical_harmonic_structures https://en.wikipedia.org/wiki/Heavy_metal_music#Typical_harm... > H

From wikipedia: https://en.wikipedia.org/wiki/Heavy_metal_music#Typical_harmonic_structures https://en.wikipedia.org/wiki/Heavy_metal_music#Typical_harm... > Heavy metal is usually based on riffs created with three main harmonic traits: modal scale progressions, tritone and chromatic progressions, and the use of pedal points. Tritones are notably present in heavy metal, as a genre, to my understanding. That's consistent with what wikipedia is saying. The tritone (6 half-steps) is generally regarded to be one of the most dissonant intervals in western music.