Just some suggestions, before you get extremely deep in scripting.
I honestly don't believe we need three types of coins (Copper, silver, gold) But then how much does it matter?
Second, and I believe this very important.
In mining there is NO SUCH THING as IRON ore. It is hematite ore, limonite ore, and megnetite.
For other substances as well, for copper, it is malachite ore. (Though Native Copper can occur.) (From memory)
Sphalerite - Zinc
Cassiterite - Tin
Galena - Lead (From memory)
Tetrahedrite is interesting, mostly copper, but noted to contain silver.
In steel smelting, look for older ways of smelting. But one way I would think of it as is.
Iron + Pig Iron + Fuel (Coke / Charcoal) + Stone high in oxygen + Heat = Steel
Metals constantly use magnesium as a alloy strengther, but that might just be far too detailed.