Enviromine has that feature IIRC
I'm pretty sure it's just buffed vanilla generation with support for common materials such as copper and tin. Don't quite me on that though.
Source: I remember at some point someone on a server I played wanted to mine yellorite and the DeepDark was of no use. That was in 1.6 though.
I believe that in the 1.7.10 dw20 pack or any other for that matter yellowrium ore is not found in the deep dark but uranium ore is found. In the dw20 pack uranium is ore dictionaried with yellowrium so if he found any it might be because of that.
The thing is that I mainly want diamonds so if anyone has any ideas for that. Please help. (Not manual mining)