Working a mine by hand is tiring; your recharge rate depends on your Endurance. It's a good idea to build a kitchen near the mines that you plan to work by hand and fill it with Endurance food.
Ore unearthed by a mine (including gems and other extras; see below) is stored in the mine until it is taken.
Sooner or later your mine will collapse. There is no way to predict when this will happen; it may take fewer than a dozen pulls, or more than several hundred. Collapsed mines must be repaired (i.e. expanded to a lower depth) before they can be worked again. The first repair will cost you 30 boards, 60 bricks, 2 canvas, and 6 water in jugs. Once you repair it, you'll be the proud owner of a level 2 mine and can work it again as usual. The deeper your mine gets, the higher the repair costs will be, especially in bricks.
There is no way to trick the system here. If you tear down a collapsed mine, and try to build a new one on the same spot, the system remembers that another mine has been there before and will prompt you to build a level 2 (or deeper) mine right away.
You can store repair materials in the mine. When you extend a mine, only the materials that are actually needed for repair for that level are used.
The costs to expand a mine to level L are:
| Boards | 15 * L |
| Bricks | 15 * L^2 |
| Canvas | L |
| Water in Jugs | 3 * L |
A table of values for each level is listed at Mine Expansion Costs. If building a new mine of level L, add 1 to L to find the building cost.
There are six types of gem: quartz, ruby, emerald, sapphire, topaz, and diamond. Every mine will produce one, and only one, type of gem. What type of gem a particular mine yields, and how frequently it will produce a gem, is randomly set when the mine is first built. (Thus, tearing down and rebuilding a mine will "re-roll" its gem-producing characteristics; even if the new mine is on the exact same spot as the old, it may yield a completely different type of gem.) Quartz is by far the most common gem produced by mines, while diamonds are the least common. Once a mine's gem type is known (i.e. once it produces its first gem), its gem type is displayed when you click on the mine.
The frequency of a mine's gem yield varies by mine. Some mines are excellent gem producers (averaging 1 gem every other pull), others are terrible (1 gem every 20 pulls or so).
In addition to gems, a mine will occasionally cough up a medium stone, or sometimes flint (3 at a time). Mines of depth 5 or deeper frequently produce coal.
Automated mines never yield gems or any other extras -- only ore (or dirt).
So, automation can be very handy. But a mine that yields lots of precious gems, or coal, is usually not worthwhile to automate. A typical candidate for automation is a mine that yields one of the more rare ores, because working those by hand is so very tedious.
Mines pollute and the more heavily they are worked, the more they pollute. Most flax and vines will not grow on polluted ground. People are also speculating about the possible negative effects of pollution on vegetables, mushrooms, livestock and so on. So, to be on the safe side, don't build your mines too close to your camp. If the soil in your camp gets polluted after all, then stop using the mines a bit. After 1-3 RL days conditions should be back to normal again.
The Mine Recovery skill may be used to restore a mine to depth 1.
Since a lot of new folks are referring to these pages right now, and getting upset when things don't work as expected, mining in Beta is TOTALLY different than on live. Please do not build a mine in beta expecting it to be the same.
This guide is taken with permission from AirmidWulf's forum post "The Somewhat Complete Guide on Ores and Mining".
(See also: Dowsing, Mine Expansion Costs, Ore Smelting)