I have double checked everywhere in the overworld, used X-Ray, everything to find any Aluminum or Silicon in the overworld. I have more mods installed with forge and I believe one of those is screwing it up.
I'm having this same problem. only difference is that aluminum is spawing whereas silicon is not
I've even duplicated the world and I've found some silicon and then went to the same exact location in my normal world and it isn't there.