Good question!!!!

Sorry, I don't have an answer, just one of the best questions I've heard asked her in a few days.

I have several metal mines in my game, so i'm also intersted to know this stuff.

Heh. I'm forcing the issue with one of my DMs, also, so if I can't find anything good here I'm making him decide. My character there has stakes in a mine, and I want to know how he decided what we made from it.

I don't have any numbers for you, just that: it depends on the game.

You should limit production to what you want your PCs to be earning from it. Maybe they only make enough to pay the workers and maybe to upkeep the castle, so that they still have to go adventuring for other wealth. I'd just find a way to use the mining to help the campaign, rather than aiming for any kind of realism.

The other thought is how rich the mine should be in comparison to the average wage of the local populace. If a mind suddenly opens up that produces more than the average farmer makes in a month, you're going to get a lot of people suddenly hoping to strike it rich. Though of course, dealing with competiting miners could make for an interesting set of side-adventures.

Unless you want the mine to be really rich, I'd say that it should produce around the same amount of money that the PCs would make if they spent all their time working in the mine rather than adventuring. That is--they pretty much break even. You could also have them gain wealth not in terms of coinage, but maybe general prestige: "You've earned enough money to be recognized by local businessmen, and to be able to found a small town" or something. So they can't buy gear with it, just gain RP effects.

The other suggestion is to base it on the profession skill. "You can practice your trade and make a decent living, earning about half your Profession check result in gold pieces per week of dedicated work." So have the dwarves make a profession check to see how much they can make, maybe giving a bonus or penalty depending on whether they've struck a rich area (this could be totally arbitrary to fit in with whatever adventure you've got going on). In short, I say make up numbers that fit the rest of the game, rather than being forced to fit the rest of the game to whatever numbers you get.

Though of course, dealing with competiting miners could make for an interesting set of side-adventures.

Not only competing miners but lawfu... I mean self-sufficiant people who might want to rob the mine... >:D

Thanks for the input!

Ah! Cool site, thanks!

From the phb, and quoted from the SRD (underline added for effect)

Like Craft, Knowledge, and Perform, Profession is actually a number of separate skills. You could have several Profession skills, each with its own ranks, each purchased as a separate skill. While a Craft skill represents ability in creating or making an item, a Profession skill represents an aptitude in a vocation requiring a broader range of less specific knowledge.
Check

You can practice your trade and make a decent living, earning about half your Profession check result in gold pieces per week of dedicated work. You know how to use the tools of your trade, how to perform the profession’s daily tasks, how to supervise helpers, and how to handle common problems.

Action

Not applicable. A single check generally represents a week of work.

Try Again

Varies. An attempt to use a Profession skill to earn an income cannot be retried. You are stuck with whatever weekly wage your check result brought you. Another check may be made after a week to determine a new income for the next period of time. An attempt to accomplish some specific task can usually be retried.

Untrained

Untrained laborers and assistants (that is, characters without any ranks in Profession) earn an average of 1 silver piece per day.

So, to my mind, I'd pay the workers a percentage opf the output, so if their average weekly earning is 10 gold pieces, you could say that this is 10% of the mine's output.

Each, or all of them...

Because if you have 10 miners that's all your profit. If the 10% is split up between all 10, then that's a sp a person, which could be low or high depending on their skills....

The amount earned varies by the skill of the miner. I meant take the GP he earned as 10% of his production.

Makes good sense. Thank you!

I ran that adventure once myself. If I recall correctly, the mine output was supposed to be equal to the costs of rebuilding the castle (materials and workers' wages) and upkeep (food, repairs, guards' wages &c.). I don't recall right now what the size of the castle was, but if you look in the Stronghold Builder's guidebook, there is a chart for costs to build/maintain castles of various sizes. Compare the size of Brightstone Keep to that chart and you should have a good number to go by.

Icon envy!