I don't mind adding lots of minerals/products, but I'm not hugely knowledgable about minerals myself and don't want to make any mistakes.
I agree that adding separate minerals/products for similars (e.g. clay / china clay / fullers earth) is unnecessary, and I don't mind adding Other Stone for those mined/quarried at a very small number of locations. Where a mineral/product was extracted from a large number of locations (e.g. Limestone) I think it is worth having that as a separate product as we currently do.
Does that sound about the right balance?
So that original list would refine to:
Talc (possibly)
Sandstone (common enough to justify classifcation)
Other Rock (for the list Tuff to Phyllite)
Sand/Gravel (for sand/gravel pits)??
my orders are to sit here and watch the world go by