Okay, this isn't an exact math, but could be if I really tried, but do to the servers being down again...I will post this incomplete.
ORE, in a nutshell:
There's basically 4 types of major ore: Copper, Iron, Mithril, and Thorium. One of these four will always be needed in creating something.
There's one supplementary: Tin. Supplmentary because its not used in anything itself, but needed with copper.
And 3 Secondaries. Silver, Gold, Truesilver. These aren't used directly for anything, but make extras.
The difference between Major and Secondary is that...12bars of mithril, 2 bar of truesilver would be needed. Also, secondaries are the rare version of major most times. (Tin - silver, Iron - gold, Mithril - truesilver)
Instead of listing every zone, I'm listing the lvls of the ore. The level of each zone is based on the level of the monsters in that zone.
So here we go, no promises with this exact.
Copper: 0-25
Tin: 10-30
Silver (rare of tin): 20-30
Iron: 25-40
Gold (rare of Iron): 35-45
Mithril: 35+
Truesilver (rare of Mithril) 40+
Thorium: 45+
So...in example: Duskwood is a lvl 25-35 zone, so you can find Tin, Silver, Iron, and Gold (I have found gold here). Not all zones follow these rules(eg, Desolace), and my numbers may not be the exact ones, but thats roughly it.
One last pointer: Run on the walls of the zone. Ore is rarely found on flatlands, generally on hills (or in mines, duh). Whats more hilly then our mountainous walls? Nothing. Goodluck, and feel free to add number corrections.