Chapter 5 - Mining Proficiency - Mining Proficiency for Dwarves - Smelting - Coins
Mining
This section contains rules for establishing and operating mines. It is assumed that most existing dwarven strongholds are built around profitable and extensive mines. These guidelines can be used for determining how successful a mine is.
Not all regions will yield something of value, regardless of the success of the proficiency roll. Examples of places where mining is a waste of time include regions of deep sand or dirt and areas of hardened lava. Streams flowing through these regions may have carried traces of ores or a gemstone, but a character with the Mining Proficiency knows that mining these areas is guaranteed to yield nothing.
If a miner seeks to excavate an area that might yield valuable material, he can make a Mining Proficiency check after surveying the area. He may determine that increasing the area of his survey sweep could yield something of value.
The length of time required for a survey will depend upon the conditions of the search. Under ideal conditions, it would take a week to survey an area of 4 square miles. Ideal conditions mean that the character is not constantly fending off goblins and marauding bandits, nor is he hunting for food. If the search is being conducted above ground, deep snow could make prospecting nearly impossible, while even a thin layer would triple the time needed. Steady rainstorms, rough terrain, and short daylight hours all interfere with a survey of the surface.
Underground searches are limited by the natural formations of caverns and passages. The area that can be examined in one week is reduced underground to 2 square miles, conditions permitting. The natural shape of the passages may be such that the character is restricted to a narrow 100-yard stretch, or that the search must be carried deeper into the earth.
After the search is completed, a proficiency check must be made by the miner. If unsuccessful, the search has either failed to discover anything of value or the character thinks he has found the best site for the mine. The miner may search the area again, seeking to verify his original findings, but it becomes increasingly more difficult; the amount of time required is multiplied by the number of surveys (the second survey takes twice as long, the third takes three times as long, etc.) and a cumulative -1 penalty is imposed on each subsequent proficiency check (-1 on the second check, -2 on the third check, etc.).
If the check is successful, the surveyor has determined the extent of mineral wealth in the area, within a reasonable margin of error. This does not guarantee a successful mine, but does locate the best site for one. If the area contains nothing of value or is unsuitable for mining, a successful proficiency check reveals that fact.
When a miner locates minerals, consult the Mining Products Table.
Mining Products Table
| Roll D100 | Product of Mine |
| 01-30 | Copper |
| 31-40 | Tin |
| 41-66 | Lead |
| 67-84 | Iron |
| 85-92 | Silver |
| 93-97 | Gold |
| 98 | Platinum |
| 99 | Mithril1 |
| 00 | Gemstones1 |
1 - Indicates only that mithril or gemstones may be present. Mithril exists deep under the earth, in dense metamorphic formations. The actual presence of mithril must be confirmed by checking the Mithril Formation Table. If gemstones are indicated, check the Gemstones Table.
Mithril Formation Table
| Roll D10 | Metal Discovered |
| 1-5 | Silver (highest quality) |
| 6-8 | Gold (highest quality) |
| 9 | Platinum (highest quality) |
| 10 | Mithril |
Gemstones Table
| D100 | Class of Stone |
| 01-25 | Ornamental |
| 26-50 | Semi-precious |
| 51-70 | Fancy |
| 71-90 | Precious |
| 91-94 | Gems |
| 95-96 | Jewels |
| 97-99 | Roll twice on this table |
| 00 | Roll three times on this table |
Quality of Mine
Because a mine has been established does not mean that it automatically yields valuable metal or gems. The quality of the ore must be determined. Even the highest quality metal requires some processing before it can be sold.
Metals
If the yield of the mine is a metal, it will probably be in the form of ore (metal-bearing rock). While pure nuggets may be discovered occasionally, a character with the Smelting proficiency must separate the metal from the ore.
The quality of the ore is equal to the number of coins that can be produced from it by a single miner in one week. A copper mine, with a rating of 200 cp, would mean that a single miner, working for one week, produces a pile of ore that can yield 200 cp of copper when smelted. The amount of coinage indicates how much is produced, not that coins must be produced.
One-thousand coins of iron, for example, equal one suit of plate armor, 100 spear heads, or 500 arrowheads.
To determine the quality of the mined ore, roll 1d10 and compare it to the result for that metal on the Ore Quality Table. This equals the coin equivalent produced per week per miner.
Ore Quality Table (Roll 1d10)
| Metal | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 101 |
| Copper | 100 | 200 | 250 | 300 | 350 | 400 | 500 | 750 | 1000 | 2000 |
| Iron | 200 | 300 | 500 | 700 | 900 | 1200 | 1600 | 2000 | 3000 | 4000 |
| Silver | 25 | 50 | 100 | 200 | 300 | 400 | 500 | 750 | 1000 | 2000 |
| Gold | 10 | 25 | 50 | 100 | 200 | 300 | 400 | 500 | 750 | 1000 |
| Platinum | 5 | 10 | 20 | 40 | 75 | 100 | 250 | 400 | 800 | 1000 |
1 - If a 10 is rolled, roll 1d10 again. If another 10 results, the mine is a pure vein of the highest quality and requires no smelting. If 1-9 results, the metal must be smelted.
Ideally, the smelted metal has the same value as its coin equivalent: i.e., 20 10-coin ingots of silver are worth 200 sp. In a true medieval economy, however, everything is negotiable. Miners may not be able to get this much for their bullion, or may get more, depending on local conditions, who the buyer is, and regional supply.
If a character sells the ore without smelting, the selling price can be no more than 25% of the value of the pure metal, and it may be as low as 5%. The asking price will depend on the difficulty of transportation and the cost of smelting the ore.
Gemstones
Newly mined gemstones are not nearly as valuable as they are after finishing. Gemstones are rough and even unrecognizable when first discovered. Characters with the Mining or Gem Cutting proficiencies can correctly identify a stone after 1d6 rounds of study.
The quality of a gemstone mine depends on the number of stones in each find and the value of the stones. The number of stones is that which one miner can excavate in one week.
The value of the stones is the average value for an uncut stone, which is 10% of its cut value. To realize the full amount from the gemstones, a miner needs to employ a character with the Gem Cutting proficiency. Some stones are more or less valuable than this amount, but the average is as accurate as we need to get to calculate the income from the mine.
The output of a gemstone mine does not remain constant, it is rolled each week to determine the worth of that week's output. The number of miners at work each week is determined before the dice are rolled.
Gemstone Quality Table
| Class of Stone | #/miner/week | Average Uncut Value |
| Ornamental | 4d10 | 1 gp |
| Semi-precious | 3d6 | 5 gp |
| Fancy | 1d12-1 | 10 gp |
| Precious | 1d10-1 | 50 gp |
| Gems | 1d6-1 | 100 gp |
| Jewels | 1d4-1 | 500 gp |
In addition to the base value of the stones mined in a given week, there is a 1% chance per week of operation that a miner will discover an exceptional stone. If an exceptional stone is found, its value is equal to the base value of the mine's stones multiplied by a d100 roll. For example, an exceptional stone found in a semi-precious stone mine is worth 10 gp (the average value of an uncut, semi-precious stone) x d100. Players may also consult the Type of Stones Table to determine the exact types of stones found.
Types of Stones Table
| Ornamental Stones | |
| 1d100 | Stone Type |
| 01-08 | Azurite |
| 09-16 | Banded Agate |
| 17-24 | Blue Calcite |
| 25-32 | Eye Agate |
| 33-40 | Hematite |
| 41-48 | Lapis Lazuli |
| 49-56 | Malachite |
| 57-64 | Moss Agate |
| 65-73 | Obsidian |
| 74-82 | Rhodocrosite |
| 83-91 | Tiger Eye Agate |
| 92-00 | Turquoise |
| Semi-Precious Stones | |
| 1d100 | Stone Type |
| 01-07 | Bloodstone |
| 08-15 | Carnelian |
| 16-23 | Chalcedony |
| 24-31 | Chrysoprase |
| 32-39 | Citrine Quartz |
| 40-47 | Jasper |
| 48-55 | Moonstone |
| 56-59 | Onyx |
| 60-67 | Quartz Crystal |
| 68-75 | Rose Quartz |
| 76-83 | Sardonyx |
| 84-91 | Smoky Quartz |
| 92-00 | Zircon |
| Fancy Stones | |
| 1d100 | Stone Type |
| 01-12 | Alexandrite |
| 13-25 | Amber |
| 26-38 | Amethyst |
| 39-51 | Chrysoberyl |
| 52-64 | Flourite |
| 65-77 | Jade |
| 78-90 | Jet |
| 91-00 | Tourmaline |
| Precious | |
| 1d100 | Stone Type |
| 01-25 | Aquamarine |
| 26-50 | Blue Spinel |
| 51-75 | Peridot |
| 76-00 | Topaz |
| Gems | |
| 1d100 | Stone Type |
| 01-25 | Garnet |
| 26-50 | Jacinth |
| 51-75 | Opal |
| 76-00 | Red Spinel |
| Jewels | |
| 1d100 | Stone Type |
| 01-25 | Diamond |
| 26-50 | Emerald |
| 51-75 | Ruby |
| 76-00 | Sapphire |
The two types of mines commonly in use are placer mines and underground mines.
Placer Mines
Placer mining involves a pan or sluice to sift gravel, dirt, sand, and water from a flowing stream or river. This technique is most commonly employed above ground, but can be conducted below. Placer mining is a relatively simple operation requiring little equipment. At the basic level, the only requirements are a character with a shallow pan and a great deal of patience.
Placer mines collect mineral deposits from underground veins eroded by water and tumbled downstream. Finally deposited in the streambed, the miner harvests them from the water. Only mineral wealth, eroded from deposits, collects along the streambed. Since erosion is slow, placer mining is much less profitable than deep mining.
Placer mines do not yield profitable amounts of copper, iron, mithral, or gemstones. Characters who have discovered gold, silver, or platinum may try to mine the deposits. Underground mines are required for all other metals and gems. To calculate the value of placer mines, determine the quality and then roll 1d4 and multiply by 10. This is the percentage of its top value the mine will yield. For example, if a gold mine could yield 100 gp per week, a placer mine will yield only 10 to 40 gp per week.
Tunnel Mines
Operating an underground, or tunnel, mine requires a great deal more work than placer mines, but the potential for wealth is much greater. Underground mining tunnels into the earth, searching for veins of ore and gem-encrusted rock that is removed and the minerals and gems then extracted.
Excavating a Tunnel Mine
Excavating a tunnel is hard work and time consuming. The rates for excavating by the various races follow. Rates are in cubic feet, per miner, per eight-hour day.
Mining Rates Table
| Type of Rock | |||
| Race of Miner | Very Soft | Soft | Hard |
| Gnoll, Halfling, Human | 75 | 50 | 25 |
| Gnome, Kobold | 80 | 60 | 30 |
| Goblin, Orc | 85 | 65 | 30 |
| Dwarf, Hobgoblin | 90 | 70 | 35 |
| Ogre | 150 | 100 | 50 |
| Hill Giant | 250 | 150 | 75 |
| Fire Giant, Frost Giant | 300 | 200 | 100 |
| Stone Giant | 500 | 350 | 175 |
A tunnel mine must follow the shifting vein of mineral through the earth. Such a path typically requires a tunnel 10 feet wide and 10 feet high.
When a miner discovers a vein, roll 1d10 and multiply by 10; this is the depth in feet needed to intersect the vein. Mining may now begin in earnest. To determine the path of the vein, roll 1d4 and consult the Mineral Vein Direction Table.
Mineral Vein Direction Table
| D4 Roll | Vein Runs |
| 1 | North-South |
| 2 | East-West |
| 3 | Northeast-Southwest |
| 4 | Northwest-Southeast |
The vein always runs at least 20 feet in the direction indicated. After each 20-foot section is excavated, roll 1d10 and check the Vein Path Alteration Table to determine the new path of the vein.
Vein Path Alteration Table
| D10 Roll | Change |
| 1-2 | Steep descent |
| 3-4 | Shallow descent |
| 5 | Curves right (10-60 degrees) |
| 6 | Curves left (10-60 degrees) |
| 7 | Continues straight |
| 8 | Shallow ascent1 |
| 9 | Steep ascent1 |
| 10 | Vein ends |
1 - If the mine starts on the surface, the first time this is rolled it is treated as descent rather than ascent.
Miners who wish to continue working the mine must follow the vein, even if it goes in a direction they do not wish to follow. If the path of the vein takes a course that makes it impossible to follow, such as emerging into thin air through a cliff face, that particular course of the mine has run out. If the vein ends in both directions, the mine is played out. This rule takes priority over the Duration of Mining Site rules.
In unusual circumstances, say a tunnel that ends at a cliff which overlooks a gorge, miners may try to pick up the vein again on the other side. The DM must decide how likely that vein is to continue, depending on the situation.
Shoring a Tunnel
A tunnel mine must be supported, or shored, with wood or stone pillars. Otherwise, sections of the tunnel will almost certainly cave in. Shoring can be done by characters with Mining Proficiency, Carpentry, or Stonemasonry proficiencies.
Each 10-foot section of tunnel requires two side and one ceiling brace, each at least 1 foot thick. If the tunnel is 10 feet wide and 10 feet high, each brace uses 30 feet of bracing material. Each shoring brace requires four hours to build.
Playing Out a Mine
Mines contain finite amounts of mineral wealth. Sometimes, this amount is enough to keep miners busy for generations. More frequently the mine plays out after a period of intensive mining.
To determine the length of time a mine will produce before depletion, roll 1d100 at the start of the mining operation. The result is the number of weeks the mine can be worked. If the result was doubles (11, 22, 33, etc.), the mine has a much longer duration. Roll 1d100 again, the result is the additional number of months the mine will produce. Add this figure to the number of weeks set by the first roll. If the second roll is also doubles, roll 1d100 a third time, the result is the number of additional years the mine is will operate. Further doubles rolls are treated as tens of years, hundreds of years, and so on.
For the sake of convenience, treat each month as three weeks and each year as 36 weeks or 12 months when totaling up the mine's longevity. Please note that a "week" is the amount of work that one miner can perform in a week. If 12 miners are engaged in excavating a mine, 12 weeks of the mine's lifetime are used up for each week of operation.
If the mine is a placer mine, disregard any doubles rolls for the duration of the find. A placer mine is always depleted after 1d100 hours of work.
In order for a mine to produce at maximum efficiency, the character in charge must make a successful Mining Proficiency roll each week of the mine's operation. If the roll succeeds, the mine produces normally. If it fails, production is reduced by half for that week. This could be the result of pilfering among laborers, a cave-in which causes the loss of valuable production time, the intrusion of some monster--an umber hulk or ankheg, perhaps--or plain old bad decisions on the part of management. The exact details should be worked into an adventure if possible; hunting the umber hulk through the tunnels or rescuing trapped miners before they suffocate.
Although overseeing a mine provides steady work, player characters will probably find it best to hire an NPC with Mining Proficiency to act as overseer, freeing themselves up for more exciting pursuits.
