I'm sure this topic has been covered in depth, but I came up with a solution for what I perceive as a massive problem with the metal in Haven and Hearth. Which is, to be succinct, it's utter overabundance. Any damn fool with a pick-axe and a bear cape can find themselves metal as it sits, and once you find metal, it's generally high livin'. You may not have the best quality stuff, but by gum you've got all the bits and bobs you need to get there.
This... Is infuriating. The most glorious part of World 3 was the ability to consolidate a resource that had a real and potent value in the world. Since that time, nothing has emerged to take it's place. Soil hang-ups can be overcome, as can the need for incredibly high quality wood (which mostly just becomes a case of wagging the dog), and even curiosities, while valuable, simply do not hold the same place of high honor that metal once held.
So what does one do for this scarcity, while retaining the ability of anyone to potentially get in on the metal game? One adds one further detail to the metal diagram... Density.
As it sits right now, you can find a vein just about anywhere, and if you found that vein, why, you're going to be getting a certain amount based on the industry setting of your miner back in ingots. Veins also are of a rather immense size as a rule (I have never personally run one out, nor stumbled across one that has been played out. I'm sure some of the bigger factions have managed). I've noticed a disturbing tendency for all of a large villages metal needs to be able to be met within a few regional grids of their home base. This? Is a redonkulous thing. Worse, that once they have acquired it, they never truly want for metal again, veins become a useless and boring thing unless they happen to be of high quality, and low hardness.
This is where Density comes in. It would require a slight refitting of the Smelter, where the output of the smelter is in fact produced in a bar below the placement grid for the ore, and where the output of the ore is tied both to the industry of the miner, *AND* the density level of the ore.
That being said...
Using this system, you may find a vein of high quality, high hardness, low density ore, that only yields about one nugget for every 3 or 4 units of successfully processed ore. (Note the Industry of the miner). This may result in a scant few nuggets of metal for a full smelter run of ore.
Rather than going into exhaustive examples:
Quality, Hardness, and Density would all exist on separate spectrums, any combination of the three is possible, and all three may in fact vary along the same vein of ore. If they do, they will do so in a logical fashion, based on the type of vein.
You may run into a cluster vein, which bears a striking resemblance to a neuron. Big ball in the center, with dendrites spreading out in every direction. The dendrites would have a declining density (but not necessarily quality) as they spread out from the epicenter. Hardness will progress however the ground lays it out naturally, it will be no indication of whether or not you're getting closer to the center.
It may just a normal vein, a slender layer of metal twisting and turning in a more or less straight line through the earth.
And any other configuration the developers see fit to include.
This would make it possible to continue to have metal largely available to everyone, but with an abundance of cheap, largely low density veins scattered throughout the world and even layers, it would increase both the difficult and overall costs of mining the same material. There would be a few rich veins distributed throughout, with heavy cores, or just thicker veins altogether, and all would require far more extensive mining of the ground than we currently have to do.
Additionally, all items... period... But in this case specifically speaking of those created out of metal would decay with use and time. This is necessary to facilitate the overall value of metal, the value of securing sources of metal of all qualities and types, and the need to constantly seek new sources as old tools wear out. The time element of decay is to make allowances for those items that never see any use, (see - The swords of those that carry them primarily as an appearance item).
I feel this, overall, would return the value to metal that it has been sorely missing, as well as make the overall mining experience more interesting and intensive, while retaining the ability of semi-casual players to have some chance of obtaining some on their own.
Just my .02