== Tonality == 

 I've analysed some black metal recently and I think there should be a section on the tonality and harmony used in black metal, i.e. uses the Diminished scale, often rather than using diminished and minor chords it uses ambiguous parallel minor thirds to create a very dark and grim atmosphere. A progression typical of the styl would go something like this: 

 I-II-I-IV-III 

 Although this sort of things is a common feature, it is not a universal one.