Darkslate - Deep Dark Concept

While reviewing the footage of the deep dark, the city and skulk growth felt out of place in the middle of a cave of deepslate. Everything under y level 0 will be mostly deepslate afterall. Instead, I thought that the deepslate that generates in the Deep Dark, should be replaced with a darker hued block. This is where darkslate comes in. It would be a dark hued, as well as a harder block to mine, then deepslate.