Page history last edited by Aryx 8 years, 5 months ago

For a look behind the curtain with all the math I did here as well, go here: Mining Math  Also has random tables for things you can see by eyeballing it, and expansions like 'shouldn't dwarves be better at mining' and 'what if I hire umber hulks to do the work'?


This work is basically derived from the AD&D 2E Complete Book of Dwarves, modified and remathed to fit into the ACKS system assumptions.


A complete, though sparse and poorly laid out, PDF can be downloaded here: ACKS Mining.pdf


For the rules from a basic user perspective, read on.



Mines are fun.  They have adventures built into every nook and cranny; following the vein can very easily break you into an underground cavern full of zombies, or any other crazy thing.  They're also a great alternative to mercantile ventures if PCs don't see themselves as trader moguls, but instead want to focus on a specific product.  In this set of random math, they can focus on mines, and metals.


The first step is for the Judge to determine whether or not the area has any mineral veins, and if so, how many are viable to mine.  This will depend on your campaign world (in the world of Athas, very few areas will have mineral veins; in the hypothetical Dwarf Heaven, every area will have multiple mines).  If you do not have a detailed geological and tectonic survey of every area in your campaign world, you have two options; you can choose or roll.


Terrain Type Mineral Veins per Hex
Clear, Grass, Scrub 1d4-1
Woods 1d2-1
River 1d2-1
Swamp 1d3-1
Mountains 2d6
Hills 1d8
Barren 1d6
Desert 1d4-1
Jungle 2d4
Underground* 1d6+1

*at a depth of 101 feet or deeper; above that, use the value for the terrain on the surface


Once the Judge knows how many veins are in an area, the next step is for them to be discovered by the potential miner (whether PC or NPC).  The potential miner must make (or have made on his behalf) a Land Surveying proficiency throw to examine the hex.  This throw takes one month under ideal circumstances, but may take longer under some conditions; for example, being attacked by monsters, being forced to provide your own food, inclement weather, etc, will all cause delays in the survey.  If the throw fails, the character fails to find any mineral veins in the area.  If the throw is successful, the character learns the number of viable mineral veins in the area. and the best location to approach one of them.  The vein will be buried 1d10*10 feet below ground, and will require an initial excavation to approach.  Further throws (requiring one week per throw, again under ideal circumstances) can survey the best approach to each other mineral vein.  (Of course, if the area has no useful mineral veins, a successful proficiency throw learns simply that.)


It is also possible to survey underground.  However, surveying underground is slower and more difficult, and will take 2 months per hex to survey and 2 weeks per hex to find additional mine approaches.  On the other hand, when already underground, the amount of excavation you need to access each mine approach is much lower, a mere 2d10 + 10 feet.


Surveying a non-pacified hex should guarantee at least one random encounter aboveground, and at least two belowground.  Surveying a pacified hex should roll for a chance of random encounter for wandering monsters aboveground, or twice belowground.


For every 500 feet of depth you travel underground, you may survey the hex for veins again.


Once the number and location of veins are known, it is important to know what type of vein has been found.  This is not learned by the initial Land Surveying throw, but requires a successful Knowledge (geology) or Craft (mining) throw. (Or any other proficiency deemed to be appropriate by the Judge.)  A failed throw results in misidentification; the Judge should roll on the Mine Type table twice, once for the true result and once for what the character believes it to be, and inform him of the false result.


Roll (d100) Mine Type
1-45 Copper
46-60 Tin
61-75 Lead
76-85 Iron
86-90 Silver
91-93 Electrum
94-97 Gold
98 Platinum
99 Mithril*
100 Gemstone**
101+ Precious***

*(roll on Mithril Formation sub-table)

**go visit the Gemstone Mines page

***(roll on Precious Formation sub-table)


Depth Modifiers to Mine Type

Depth Modifier
0-100 feet 0
101-500 feet +20
501-1000 feet +30
1001-2000 feet +40
2001-3000 feet +50


Beyond 3000 feet of depth, the temperature becomes problematic to deal with.  Should you be able to deal with this (it is expected to be approximately 45C/110F at a depth of 3000 feet), add an additional 10 to your roll for each 1000 feet of depth.  Note that every 1000 feet of depth also increases the temperature by 10C.  (The actual maximum depth before you hit mantle ranges, in the continental crust, from approximately 20 to 30 miles thick; unless you are fire elementals, balrogs, or other such creatures, the heat and pressure will stop you from mining long before you reach this limit.)


Mithril Formation Sub-Table

Roll (d10) Result
1-4 Silver (highest quality)
5-7 Electrum (highest quality)
8 Gold (highest quality)
9 Platinum (highest quality)
10 Mithril


If your campaign is not using mithril or any other fantastic metal, and you roll Mithril on the Mine Type table, roll on the Mithril Formation sub-table as normal.  However, if you then roll Mithril again, treat it as Platinum (highest quality).


Precious Metals Sub-Table

Roll (1d10) Type
1-3 Silver
4-5 Electrum
6-7 Gold
8 Platinum
9 Mithril*
10 Gemstone

*roll on Mithril Formation sub-table


After you determine what type of mine you have, the next step is to roll for the quality of the ore found in this mine.


Roll (1d20) Quality
1 1
2-3 2
4-5 3
6-8 4
9-12 5
13-15 6
16-17 7
18 8
19 9
20 10
21+ Roll on High Quality sub-table


Depth Modifiers to Quality

Depth Modifier
0-100 feet 0
101-500 feet +1
501-1000 feet +2
1001-2000 feet +3
2001-3000 feet



If delving beyond 3000 feet, add an additional +1 per 1000 feet.



High Quality Sub-Table

Roll (1d10) Quality
1-2 7
3-5 8
7-8 9
9-10 10



The quality of a mine determines what percentage of the ore is metal; multiply the quality by 10, and the ore is that percentage metal.  (A range of 10% to 100%).  Quality 10 ore is pure metal, not ore at all, and does not require smelting.  All other qualities of ore must be smelted to separate the metal from the ore.


A mine is worked by a team of 1 master miner, 2 journeyman miners, 4 apprentice miners (these preceding characters all have varying ranks of Craft (Mining)), and 10 unskilled laborers.  Together, the amount of work this team can perform in a week comprises a miner-week of work.  One miner-week is the standard unit of work used in these calculations and tables.  Should you prefer to use a monthly scale (miner-month instead of miner-week), multiply all appropriate numbers by 4.  (This introduces a little bit of roundoff error, but it is acceptable in my mind.)  Paying this mining team costs 40 gp per week.


Each type of mine has a different rate of quarrying.  One miner-week extracts a variable amount of ore from the mine, depending on which type it is.  Copper, tin, lead, and iron are common metals; thus, it requires 100 stone of metal to fill one load of common metal (with a base value of 200 gp.)  Silver, electrum, gold, and platinum are precious metals; one load weighs only 4 stone and has a base value of 600 gp.  However, that is the actual metal weight.  The weight of ore required to smelt that amount of metal will vary based on the quality of the mine; at 50% quality, it will take 200 stone of ore to smelt out 100 stone of metal.  The Mining Progress table shows the amount of ore that will be extracted by each miner-week of work.


Mine Type Ore Mined per Week (Stone)
Copper 50
Tin 100
Lead 150
Iron 200
Silver 2
Electrum 4
Gold 6
Platinum 8
Mithril 32


In addition to extracting the listed weight of ore, the miners will excavate the tunnel further.  A standard mining tunnel is 10 feet high and 10 feet wide.  Each miner-week of work will lengthen the tunnel by 2 feet.  In addition, every 10 feet of tunnel length will have shoring braces installed, to keep the tunnel from collapsing on the workers.


Once the ore is extracted, it must be smelted to extract the metal from it.  This requires a smelter, and an expense of both materials and manpower.  The end result, however, is that in addition to the cost of the smelter, it costs 1 gp to smelt 20 stone of common ore and 10 gp to smelt 1 stone of precious ore.


A small smelter costs 1,000 gp to set up and can process 20 stone of ore per week.

A medium smelter costs 4,000 gp to set up and can process 100 stone of ore per week.

A large smelter costs 16,000 gp to set up and can process 500 stone of ore per week.


If you do not wish to set up and run the smelters yourself, you may be able to find a smelting operation who is willing to smelt your ore for you.  Failing that, you can simply sell the ore.  If you wish to find someone to smelt your ore for you, use the rules for finding a shipping contract (ACKS page 144).  They will charge you a base price of 5 gp per 20 stone for common ore, or 50 gp per stone for precious ore.


Multiply your weight of ore by the quality of your vein to determine the amount of metal you have after smelting.  Should you not desire to smelt your ore, you can sell it as raw ore instead.  Raw ore is worth 25% of the value it would hold if it were smelted.  (Thus, if you had 200 stone of 50% quality tin ore, you could smelt it to make 100 stone of tin.  100 stone of tin would be worth 200 gp.  Your 200 stone of tin ore is therefore worth 25% of 200, or 50 gp.)


Now that you know how your mine works in play, you need to know how long it can be worked for before it is played out.  To determine this, roll 1d100.  If you did not roll doubles (11, 22, 33, etc), then the mine can be worked for a number of miner-weeks equal to your roll.  (Thus, if you rolled a 37, and you have a single mining team on the vein, it can be worked for 37 weeks before being played out.)  If you did roll doubles, however, note your roll and roll again; the mine can be worked for a number of miner-weeks equal to the original roll, and a number of miner-months (four miner-weeks) equal to the original roll.  If you rolled doubles again, roll yet another time, for miner-years.  Should you roll doubles a third time, roll again, for miner-decades, and continue if you should continue to roll doubles with miner-centuries, miner-millennia, etc.  As you can see, most mines will play out within a year, but some will continue to produce for generations.  (A high-quality platinum mine with a duration in miner-centuries is the kind of thing kings and emperors go to war over.)


Mineral veins do not usually run in a straight line for their entire lifetime; they twist and turn.  Should you care to follow the path of the vein (usually appropriate for mines that the characters are personally managing and might have underground adventures inside), use the following tables.


Mineral Vein Direction Table

Roll (1d4) Direction
1 North-South
2 East-West
3 Northeast-Southwest
4 Northwest-Southeast


The vein will always run at least 20 feet in the direction indicated.  After each 20-foot section is excavated (10 miner-weeks of work), roll 1d10 and consult the Vein Path Alteration Table.  In addition, after each 20 foot section is excavated, the Judge should check for random encounters as appropriate for the terrain.  (In general, it is expected that the deeper you are, the more likely a random encounter is and the more devastating that encounter will be.)


Vein Path Alteration Table

Roll (1d10) Vein Path
1-2 Steep descent
3-4 Shallow descent
5 Curves right (1d6*10 degrees)
6 Curves left (1d6*10 degrees)
7 Continues straight
8 Shallow ascent*
9 Steep ascent*
10 Vein ends

*if this mine starts 100 feet or fewer underground, the first time this is rolled, treat as descent rather than ascent


A shallow ascent or descent climbs or falls 1 foot per 2 feet of length excavated (thus, over the course of its 20 foot length before rolling for a new direction, the elevation will change by 10 feet.)  A steep ascent or descent climbs or falls by 1 foot per foot, thus 20 feet before rolling again.


If the vein's path takes it to a place where it cannot be reached (such as open air or a lake of lava), the vein ends.  At the Judge's discretion, it might be possible to pick up the vein on the other side of the obstacle, such as a small gorge.  If the vein ends in both direction, the mine is played out; this takes precedence over the ordinary rules for the duration of the mine.


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