I'd suspect that most people looking for a given location will start by entering the name. I'd follow that by suggesting that most people will know the mine in question by its principal product, which in the great majority of cases will be its greatest product by tonnage over most if not all of its life.
Tonnage is the only meaningful way of defining a mine's capacity. Professionals talk about tonnages, in the same way that oil people talk about barrels, because they are a far more meaningful description of the scope and nature of operations than final value of finished product. Apart from anything else, any mine selling part-processed ore, or sending ore for smelting under contract, isn't getting the full sale price anyway
Secondary products are a confusing issue at best - is Boulby a "salt mine", because it certainly produces salt?
"Boulby Potash Mine" gets my vote as a logical and sufficient format
''the stopes soared beyond the range of our caplamps' - David Bick...... How times change .... oh, I don't know, I've still got a lamp like that.