Keeping in mind that I already support this idea from Grieger, here:
Adventurer Prospecting, I have something in another vein (no pun intended) to propose:
Let's have some sort of "cheat mode" legends mode map view of all of the minerals that now are obviously geographically localized. Let players who are really interested in seeing where the iron ore, the coal deposits, even the microcline in the world are located geographically.
It lets the players who are really interested in doing serious study of the way geography is handled in this game (and how it can be playtested into becoming better) have a useful tool for gathering data, and comparing against real-world geology, and discussing ways to better model these geological effects.
That said, and I'll tie this in with Grieger's idea, and contribute to that one, as well, but we should have some sort of way in which some of this data is hidden from players in-game until explored, but giving the player more way to gain data about "revealed" areas on the map so that they aren't blindly digging at "some metal" without knowing what metal it is. (How do you know metal's even there without knowing what kind of ore it is? Do you just use a giant metal detector on the whole world?)
Give us a means of searching for specific things in the site finder function - maybe our dwarves are sent out on a mission to explore for copper veins when scouts have reported finding copper nuggets lying around in small quantities on the ground. Our civilization has plenty of tin and zinc, and seeks to set up a lucrative bronze and brass manufacturing business to trade with the rest of the world... but you need to know it's
copper before you embark, and not just "some metal".
A search feature that lets us choose one specific mineral to search for in areas knowable (and let some parts of the map have "unexplored" markings where the game doesn't say there is or isn't any ore, but that it's just unexplored), so that you can specifically say "I'm going to set up a copper mine, where is the copper?" Then, you can just choose which of the sites that you actually know will have copper will have other features you find most acceptable or at least the least undesirable, if you choose to live in a desert just to avoid an aquafer.