Alternate Stone Caves & More Ore Variants

To further diversify the overworld, there could be sub-surface biomes consisting fully of an alternate stone type. These already generate in large patches and will have a larger presence in after the Caves and Cliffs update, and therefore would only add to the aesthetics of the world...unless (some?) of the other stone types were added to crafting recipes that previously have used cobblestone only (but now we're getting into 'stone+pickaxe=cobblestone, but granite+pickaxe=granite, uncobbled'...I feel like cobbled versions of all of these stones would add far too much complexity). These granite/andesite/diorite caves could feature blob inclusions of natural stone too.

Additionally, ores in these sections of the world would be embedded into the texture of its respective stone, similar to the deepslate ore variants. This would apply to granite, diorite, andesite, but not calcite, or could be unique to diorite and andesite, for example. 

I imagine this to take over areas as large as surface biomes, but not necessarily related to specific biomes themselves. They would stretch from y=~0 to y=270, allowing mountains to have even more variation, more parallel to the real world.