So I made a spreadsheet and included a wide variety of values such as rarity, "shininess", economic use, and so on. I calculated the values for each metal and refined the names:
Metal Rarity Class Quality Value
Coal 0.5 0 1
Tin 1 2 50 2
Copper 1 2 60 2
Zinc 2 1 3
Base Pewter 2 3 4
Lead 2 1 20 3
Nickel 2 1 60 6
Fine Pewter 3 3 8
Pig Iron 3 1 8
Magnesium 2 1 80 8
Bronze 2 2 100 9
Brass 3 3 9
Nickel Silver 3 3 40 12
Iron 3 2 100 14
White Gold 4 3 40 20
Silver 4 3 50 24
Steel 4 2 120 27
Electrum 5 3 27
Gold 5 3 30
Fine Steel 6 2 150 40
Platinum 6 3 50
Rarity: Each level of rarity is roughly exponentially more rare than the last.
Class: 0: Fuel. 1: Economic. 2: Tool. 3: Precious.
Quality: The metal's % of weapon damage. No entry means no weapons. Lead can only be used for bolts.
Value: Cost in Crowns. This was calibrated so that gold is the same as before; it accounts for many of the metal's useful properties, but dwarves still like a steel floor over a silver one, because it's "economically" valuable.
Bars per Ore Clump:
Metal Rarity Poor Norm Native
Coal 0.5 0.7 2 10
Tin 1 0.5 1.5 8
Copper 1 0.5 1.5 8
Zinc 2 0 1 5
Lead 2 0 1 5
Nickel 2 0 1 5
Magnesium 2 0 1 5
Iron 3 0.1 1 4
Silver 4 0 0.5 4
Gold 5 0 0.25 4
Platinum 6 0 0 3
As you can see, the economic metals are kind of rare- however, only a few bars are required to produce a much greater amount of the end alloy. Tin and copper are both very common, and thus Bronze should be a good metal to use, as it is equal to iron in weapon quality. That said, Bronze requires more work to make useful. Iron can be used much more quickly. Steel is rare and has 120% the damage of iron. Fine Steel (that has been treated with zinc and magnesium) is 150%, and costs almost as much as Platnium, which now only forms in small clusters. Electrum costs exactly the same as Steel, making it a sensible trade metal.
All alloying requires finished bars, because most metals have several ores and it is clutter-y.
Oh, and there will be a way to use a metal- probably Magnez., to treat stone and turn most kinds or rock into magma-proof stone for mechanisms. Naturally, it will be difficult and expensive.