Mining

==In-Game Text==
"King Under The Mountain,
Crowned in stone and steel,
His deep mine and torch-lit halls."
You have a basic understanding of the common minerals, and of how to mine them, and can thus construct Mine Shafts and Supports provided you have found appropiate materials.
==What it does==
Mining allows you to mine underground for minerals using an axe or a pickaxe. It's required to construct Mine Holes and Mine Supports. It also unlocks Tunneling skill with which you are able to construct Stone Columns.
==How to mine==
To begin mining, you must first build a Mine Hole or find a Cave. Have a Stone Axe, Metal Axe or a Pickaxe equipped and use and click on a wall. Walls within the 49 tiles (7x7) of a cave entrance cannot be mined. Be careful, as mining without supports may cause a cave-in that can cause HHP and SHP damage and will kill you if you get hit by too many.
Mining drains stamina based on the type of the tool used, it's quality and the hardness of the tile relative to a character's mining ability. Make sure to bring plenty of drink to restore stamina quickly.
Using a torch or Miner's helmet for light will help drastically when mining, particularly when working older mines whose ore deposits are located far away from the minehole. Note however that using a pickaxe requires both hands, thus making a miner's helm the only portable light source that can be used. (Note: Use of current custom clients with Night vision negates the need for light sources if turned on.)
The world consists of multiple layers--the surface and five underground layers. Caves and mines all are part of the same underworld; a hearthling can tunnel from one mine or cave to another. In the underworld, if a hearthling selects 'mine' and clicks on a wall, he or she will attempt to chip out the wall, extracting Ore or stones, depending on the what mineral node it is.
Note:Initial Cave walls are neutral, and will not give stone or ore (except for occasional Cat Gold). They must be mined to expose what minerals are directly around it. Minerals (Stone and Ore) exist in nodes. Various stone nodes build almost all of the underground. Sometimes ore nodes will intersect cave walls, and sometimes you have to dig into the wall for some distance before finding ore. For you to mine a cave wall, you need to click on the wall that is at least 50 tiles from an entrance. You can also use Rustroot Extract to find ore in the layer below you.
Whether the hearthling is able to extract ore or stones depends on the hardness of the wall. That is to say, some wall tiles will require more strength (and/or better tools) to extract ore or rock from. If the hearthling has enough strength to mine it, the tile will be converted into floor. 
The higher your strength is and the better quality tools you use, the faster the mining spot will be mined. Also, mining spots contain layers, which means that each tile can be mined multiple times before it converts to floor. Each time you mine there is a chance to get stone or ore. Whether it's ore or stone depends entirely on tile - tile that belongs to vein will not give stones, and tile that does not belong to vein will not give ore. Mined stones and ore are automatically placed in inventory, or dropped to the ground if you lack the space in inventory.
Depending on the hardness of the wall compared to the quality of your tool and your strength, you will start to mine that wall or will receive an error message such as the following.
Messages that occur while mining (each message means you need 10-15 more Mining ability to mine succesfully):
* You don't even manage to scratch that rock.
* That rock is very much too hard for you to mine.
* That rock is much too hard for you to mine.
* That rock is slightly too hard for you to mine.
* That rock is just slightly too hard for you to mine.
The ability to mine out walls easier scales with Mining Ability , calculated in W8 as \sqrt {Strength * avgTool}. Note that the tool's average is calculated based on double the qualities for pickaxes and normal qualities for axes. Formula for it is suspected to be AvgTool = \sqrt[2]{\frac{Essence^2+Substance^2+Vitality^2}{3}} for axes or double that for pickaxes. Said formula has also been affectionately referred to as "the whole square average thinger", it's a technical term.
Example: You have a q 20/20/20 Pickaxe (remember that pickaxe quality counts double in the formula) and 60 Strength. Your mining ability would equal to sqrt(60 * 40) = ~50 Mining ability. Let's assume you tried to mine a wall and received "That rock is much too hard for you to mine" message. That means you would need at least 80 or more Mining ability to start mining that wall.
Using a better quality tool and better strength means more tiles to mine available. Strength can be increased by equipment such as a Bear Tooth Talisman, Bear Cape or rings: Forge Ring and Thane's Ring
==Safety and Cave-ins==
Note: Cave-ins currently do not cause death, but they can destroy some objects like stockpiles if a boulder falls on them.
===Mining with supports===
To mine without any risk of cave-in you need to be mining a tile where the centre of the tile is covered by a Mine Support or a Stone Column. To see the radius of a support you can go to Build -> Buildings & Construction then choose a support and hover it over a built support so they coincide. Or use a custom client to see them at all times.
You may also safely mine some tiles around a minehole entrance. According to jorb:
The minehole entrance is a support with the same radius as a normal wooden support. ~~Jorb 09 Dec. 2015
===Mining without supports===
You can mine without supports, though be aware that some tiles will cause cave-ins. Even some initial cave walls can cause one.
There is a method to avoid them though. It is somewhat similar to the "Minesweeper" game. Some tiles will cause dust particles to fall from the ceiling when mined. That means one or more of the 8 tiles around the tile (3x3 square with the said tile in center) you just mined will cause a cave-in. So if a tile doesn't cause particles to fall, it means that the 8 tiles around it are safe to mine (unless it itself is a cave-in tile, then it won't cause particles to fall ).
See Sevenless' guide to haven and hearth for more info on this method.
==Mining Difficulty and Ore Quality==
Underground there are 3 types of mining related nodes. Ore veins, Rock quality and Hardness nodes. These nodes are all placed randomly and have no relation to each other except under chance conditions. All rock that is mined will be of the quality equal to the rock quality node (or the base quality if there is no node) of that area. This applies to both stones mined from "empty" rock and ore mined from an ore vein. Finding a soft, high quality ore vein is therefore a very good stroke of luck.
There is only one relation between hardness and quality. As you descend levels of the world, each one gains base quality and base hardness. Quality potential goes up each layer significantly, however it is unknown the exact amount hardness goes up.