The color has also led to the nicknames brass, brazzle, and brazil, primarily used to refer to pyrite found in coal.

[8][9] The name pyrite is derived from the Greek πυρίτης λίθος (pyritēs lithos), 'stone or mineral which strikes fire',[10] in turn from πῦρ (pŷr), 'fire'.

[11] In ancient Roman times, this name was applied to several types of stone that would create sparks when struck against steel; Pliny the Elder described one of them as being brassy, almost certainly a reference to what is now called pyrite.

[16] Pyrite is used with flintstone and a form of tinder made of stringybark by the Kaurna people of South Australia, as a traditional method of starting fires.

Thermal decomposition of pyrite into FeS (iron(II) sulfide) and elemental sulfur starts at 540 °C (1,004 °F); at around 700 °C (1,292 °F), pS2 is about 1 atm.

[19] A newer commercial use for pyrite is as the cathode material in Energizer brand non-rechargeable lithium metal batteries.

[23][24] Pyrite has been proposed as an abundant, non-toxic, inexpensive material in low-cost photovoltaic solar panels.

Marcasite jewelry, using small faceted pieces of pyrite, often set in silver, has been made since ancient times and was popular in the Victorian era.

[27] At the time when the term became common in jewelry making, "marcasite" referred to all iron sulfides including pyrite, and not to the orthorhombic FeS2 mineral marcasite which is lighter in color, brittle and chemically unstable, and thus not suitable for jewelry making.

[29] In July 2020 scientists reported that they have observed a voltage-induced transformation of normally diamagnetic pyrite into a ferromagnetic material, which may lead to applications in devices such as solar cells or magnetic data storage.

[32] In 2021, a natural pyrite stone has been crushed and pre-treated followed by liquid-phase exfoliation into two-dimensional nanosheets, which has shown capacities of 1200 mAh/g as an anode in lithium-ion batteries.

[33] From the perspective of classical inorganic chemistry, which assigns formal oxidation states to each atom, pyrite and marcasite are probably best described as Fe2+[S2]2−.

The Fe ions are usually considered to be low spin divalent state (as shown by Mössbauer spectroscopy as well as XPS).

The missing center of inversion at S lattice sites has important consequences for the crystallographic and physical properties of iron pyrite.

This reflects the fact that the covalent bond in the sulfur pair is inadequately accounted for by a strictly ionic treatment.

[42] Pyrite can also form shapes almost the same as a regular dodecahedron, known as pyritohedra, and this suggests an explanation for the artificial geometrical models found in Europe as early as the 5th century BC.

[43][clarification needed] Cattierite (CoS2), vaesite (NiS2) and hauerite (MnS2), as well as sperrylite (PtAs2) are similar in their structure and belong also to the pyrite group.

These oxidation reactions occur more rapidly when pyrite is finely dispersed (framboidal crystals initially formed by sulfate reducing bacteria (SRB) in argillaceous sediments or dust from mining operations).

An example of acid rock drainage caused by pyrite is the 2015 Gold King Mine waste water spill.

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.

[51] In early 2009, problems with Chinese drywall imported into the United States after Hurricane Katrina were attributed to pyrite oxidation, followed by microbial sulfate reduction which released hydrogen sulfide gas (H2S).

[52] In the United States, in Canada,[53] and more recently in Ireland,[54][55][56] where it was used as underfloor infill, pyrite contamination has caused major structural damage.

Normalized tests for construction aggregate[57] certify such materials as free of pyrite or marcasite.

It is a common accessory mineral in igneous rocks, where it also occasionally occurs as larger masses arising from an immiscible sulfide phase in the original magma.

[2] Pyrite and marcasite commonly occur as replacement pseudomorphs after fossils in black shale and other sedimentary rocks formed under reducing environmental conditions.