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 smelter 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
10*
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

* 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
#/dwarf
Average
Stone
/week
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

Table of Contents