What is Pyrite?

Did you know...

Fire was pyrite’s most prominent gift to human society. Sparks are created when pyrite is struck against metal or a hard surface and this was one of the earliest methods humans discovered to create flame. Pyrite’s name comes from the Greek phrase, ‘pyrite lithos,’ which means ‘stone which strikes fire.’ Its brilliant metallic luster and brassy to golden color not only makes pyrite stand out from its surrounding rock, but has also caused it to be mistaken for gold by people unfamiliar with the real thing. Sometimes cruelly known as ‘fool’s gold,’ pyrite is actually much harder than gold and often has flat crystal faces that would not occur in real gold. Although no longer considered a valuable mineral in its own right, pyrite in a rock often signals the presence of other hydrothermal minerals and metal ores that do have significant value.

Pyrite is a brass-yellow mineral with a bright metallic luster. It has a chemical composition of iron disulfide (FeS2) and is the most common sulfide mineral. It forms at high and low temperatures and occurs, usually in small quantities, in igneous, metamorphic, and sedimentary rocks worldwide.

The name "pyrite" is after the Greek "pyr" meaning "fire." This name was given because pyrite can be used to create the sparks needed for starting a fire if it is struck against metal or another hard material. Pieces of pyrite have also been used as a spark-producing material in flintlock firearms.

Pyrite has a nickname that has become famous - "Fool's Gold." The mineral's gold color, metallic luster, and high specific gravity often cause it to be mistaken for gold by inexperienced prospectors. However, pyrite is often associated with gold. The two minerals often form together, and in some deposits pyrite contains enough included gold to warrant mining.

In Our Earth: The Geologic Importance of Pyrite
Although it is not a significant rock-forming mineral, pyrite is very widespread and a common accessory mineral in many rock types. In igneous rocks, pyrite may be disseminated throughout the rock or concentrated in layers if the magma cooled slowly enough for crystals to settle out. Pyrite is also common in contact metamorphic settings or disseminated through sedimentary rocks as a replacement of other minerals. Although pyrite occurs in most hydrothermal veins, it is particularly abundant in sulfide deposits. In fine-grained or organic-rich sedimentary rocks, pyrite may even form discrete pyrite concretions or flattened discs called ‘pyrite dollars’.

In calcite and quartz veins, pyrite is commonly associated with chalcopyrite and other sulfide minerals and metallic ores. Pyrite oxidizes to other iron sulfate minerals that in turn alter to limonite, so the presence of a weathered ‘rusty’ limonite layer may indicate the presence of pyrite in the underlying rock.

Pyrite and Coal Mining
Sulfur occurs in coal in three different forms: 1) organic sulfur, 2) sulfate minerals, and 3) sulfide minerals (mostly pyrite with minor amounts of marcasite). When the coal is burned, these forms of sulfur are converted into sulfur dioxide gas and contribute to air pollution and acid rain unless they are removed from the emissions. The sulfide mineral content of the coal can be reduced by heavy mineral separation, but this removal is expensive, results in a loss of coal, and cannot be done with 100% efficiency.

The sulfide minerals in coal and its surrounding rocks can produce acid mine drainage. Before mining, these minerals are deep within the ground and below the water table where they are not subject to oxidation. During and after mining the level of the water table often falls, exposing the sulfides to oxidation. This oxidation produces acid mine drainage which contaminates groundwater and streams. Mining also breaks the rocks above and below the coal. This creates more pathways for the movement of oxygenated waters and exposes more surface area to oxidation.

i found some pyrite mine in our area advice me what to do.