Minerals and ore

Pyrite:
The mineral pyrite, or iron pyrite.


This mineral's metallic luster and pale brass-yellow hue give it a superficial resemblance to gold, hence the well-known nickname of fool's gold. The color has also led to the nicknames brass, brazzle, and Brazil, primarily used to refer to pyrite found in coal.


Fool´s gold:
It is distinguishable from native gold by its hardness, brittleness and crystal form. Natural gold tends to be anhedral (irregularly shaped), whereas pyrite comes as either cubes or multifaceted crystals.

Hazards:
Iron pyrite is unstable in the natural environment: in nature it is always being created or being destroyed. Iron pyrite exposed to air and water decomposes into iron oxides and sulfate. These reactions occur more rapidly when the pyrite is in fine crystals and dust, which is the form it takes in most mining operations.

Acid drainage
Sulfate released from decomposing pyrite combines with water, producing sulfuric acid, leading to acid rock drainage and potentially acid rain.

Dust explosions
Underground coal mines in high-sulfur coal seams have occasionally had serious problems with spontaneous combustion in the mined-out areas of the mine. Why this happens is unsure, but experienced miners believe Pyrite in crystal or dust form may react to fresh air somehow.

Dwarven engineering:
In dwarven coal mines, limestone dust is sprayed onto the exposed coal surfaces to reduce the hazard of dust explosions. This has the secondary benefit of neutralizing the acid released by pyrite oxidation and therefore slowing the oxidation cycle described above, thus reducing the likelihood of spontaneous combustion. In the long term, however, oxidation continues, and the hydrated sulfates formed may exert crystallization pressure that can expand cracks in the rock and lead eventually to roof fall.

Marketing and uses of pyrite:
Dwarves have the skill to mine pyrite safely and effectively. They have also many pyrite veins in Barbandos which gives them a economic advantage on selling the mineral to outsiders.

Pyrite acts as a popular source of ignition in firearms, most notably the wheellock, where the cock held a lump of pyrite against a circular file to strike the sparks needed to fire the gun. Pyrite was discovered not many years ago, and is quite valuable to merchants.

Iron pyrite can be heaped up and allowed to weather. The acidic runoff from the heap can then be boiled with iron to produce iron sulfate. In the first decade after it was discovered such leaching began to replace the burning of sulfur as a source of sulfuric acid. If one can find more pyrite veins it could become the dominant method, avoiding the production of sulfuric fumes.

Pyrite remains in commercial use for the paper industry, and in the manufacture of sulfuric acid.