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Pyrite

earth science Maturity 7-9 Next article →

Pyrite is a common mineral known as iron pyrite. Its chemical formula is FeS2, which means it is an iron disulfide.

2780M-pyrite1
2780M-pyrite1

It is the most abundant sulfide mineral on Earth. Many people call it "fool's gold" because of its metallic luster and pale brass-yellow color. This appearance makes it look very similar to real gold. However, the two minerals are very different. Gold is malleable, meaning it can be shaped without breaking. Pyrite is brittle, so it will shatter if you try to bend it.

Pyrite under Normal and Polarized light
Pyrite under Normal and Polarized light

The name pyrite comes from the Greek word "pyrites." This means "stone or mineral which strikes fire." This name describes how the mineral behaves when struck against steel. In ancient Roman times, people used various stones to create sparks. By the time of Georgius Agricola in the 1500s, the term referred to all sulfide minerals. The mineral's ability to create sparks led to many historical uses. For example, the Kaurna people of South Australia used pyrite with flintstone to start fires.

Stolna pri Perneku
Stolna pri Perneku

In the 16th and 17th centuries, pyrite was used in early firearms called wheellocks. A small sample of pyrite was placed against a circular file. The friction from the file created the sparks needed to fire the gun. Pyrite has also been used for chemical manufacturing since classical times. People used it to make copperas, which is ferrous sulfate. They did this through a process called heap leaching. They heaped up pyrite and allowed it to weather. The resulting acidic runoff was boiled with iron to produce iron sulfate. By the 19th century, this became the main method for making sulfuric acid.

GoldinPyriteDrainage acide
GoldinPyriteDrainage acide

Pyrite has a very specific crystal structure. It is a cubic structure where iron atoms form a face-centered cubic sublattice.

FeS2structure
FeS2structure

In this structure, the sulfur atoms do not sit alone. Instead, they occur in pairs called persulfide units. Because of these S-S bonds, some scientists call it iron persulfide. The iron atoms are bonded to six sulfur atoms. This creates a shape called a distorted octahedron. This structure was one of the first to be solved using X-ray diffraction. It is a prototype for many other similar compounds in science.

Modern technology uses pyrite for its electronic properties. Pyrite is a semiconductor, which means it can conduct electricity under certain conditions. It has a band gap of 0.95 eV. In the early 20th century, people used pyrite as a mineral detector in radio receivers. These were called crystal detectors. They were very sensitive and dependable before vacuum tubes were invented. Today, pyrite is used as a cathode material in certain lithium metal batteries. Scientists are also studying it for use in photovoltaic solar panels. They want to create thin-film solar cells made entirely of pyrite.

Pyrite can grow in many interesting shapes. It often forms simple cubes or raspberry-shaped masses called framboids. Sometimes it forms a shape called a pyritohedron. A pyritohedron looks like a dodecahedron with twelve sides.

Pyrite elbe
Pyrite elbe

Pyrite is also found in association with real gold. Sometimes, a large amount of gold is actually trapped inside the pyrite. This is called "invisible gold." Even though it is called fool's gold, it can be a source of real wealth. China is currently the largest market for imported unroasted iron pyrites. They make up 65% of global imports.

Recent research has opened new doors for this mineral. In 2020, scientists found that voltage can change pyrite. It can turn from a diamagnetic material into a ferromagnetic material. This could help create new types of magnetic data storage. Researchers at Trinity College Dublin also studied how to peel pyrite into very thin layers. They call this liquid-phase exfoliation. They turned bulk pyrite into two-dimensional nanosheets. These nanosheets worked well as an anode in lithium-ion batteries. This shows that even an old mineral can lead to new discoveries.

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🖼️ Images & Media (6)
File:2780M-pyrite1.jpg
2780M-pyrite1.jpg
File:Pyrite under Normal and Polarized light.jpg
Pyrite under Normal and Polarized light.jpg
File:Stolna pri Perneku.jpg
Stolna pri Perneku.jpg
File:FeS2structure.png
FeS2structure.png
File:Pyrite elbe.jpg
Pyrite elbe.jpg
File:GoldinPyriteDrainage acide.JPG
GoldinPyriteDrainage acide.JPG
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