The mineral pyrite ( / ˈ p aɪ r aɪ t / PY -ryte ), or iron pyrite , also known as fool's gold , is an iron sulfide with the chemical formula Fe S 2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral .
61-524: Pyrite'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 . The name pyrite is derived from the Greek πυρίτης λίθος ( pyritēs lithos ), 'stone or mineral which strikes fire', in turn from πῦρ ( pŷr ), 'fire'. In ancient Roman times, this name
122-415: A Lambertian reflector . An example is kaolinite . A distinction is sometimes drawn between dull minerals and earthy minerals, with the latter being coarser, and having even less lustre. Greasy minerals resemble fat or grease. A greasy lustre often occurs in minerals containing a great abundance of microscopic inclusions, with examples including opal and cordierite , jadeite . Many minerals with
183-435: A "vitreous greasy" lustre). Some minerals exhibit unusual optical phenomena, such as asterism (the display of a star-shaped luminous area) or chatoyancy (the display of luminous bands, which appear to move as the specimen is rotated). A list of such phenomena is given below. Adamantine minerals possess a superlative lustre, which is most notably seen in diamond . Such minerals are transparent or translucent, and have
244-435: A Fe face-centered cubic sublattice into which the S 2 ions are embedded. (Note though that the iron atoms in the faces are not equivalent by translation alone to the iron atoms at the corners.) The pyrite structure is also seen in other MX 2 compounds of transition metals M and chalcogens X = O , S , Se and Te . Certain dipnictides with X standing for P , As and Sb etc. are also known to adopt
305-628: A close-packed cubic unit cell much like the mineral halite of the halide mineral group. Zinc, cadmium , iron , copper , antimony , arsenic , bismuth and selenium also occur in variable amounts in galena. Selenium substitutes for sulfur in the structure constituting a solid solution series. The lead telluride mineral altaite has the same crystal structure as galena. Within the weathering or oxidation zone galena alters to anglesite (lead sulfate) or cerussite (lead carbonate). Galena exposed to acid mine drainage can be oxidized to anglesite by naturally occurring bacteria and archaea , in
366-597: A foul odor and corrosion of copper wiring. In the United States, in Canada, and more recently in Ireland, where it was used as underfloor infill, pyrite contamination has caused major structural damage. Concrete exposed to sulfate ions, or sulfuric acid, degrades by sulfate attack : the formation of expansive mineral phases, such as ettringite (small needle crystals exerting a huge crystallization pressure inside
427-458: A glassy lustre. A list of these terms is given below. Lustre varies over a wide continuum, and so there are no rigid boundaries between the different types of lustre. (For this reason, different sources can often describe the same mineral differently. This ambiguity is further complicated by lustre's ability to vary widely within a particular mineral species). The terms are frequently combined to describe intermediate types of lustre (for example,
488-510: A greasy lustre also feel greasy to the touch. Metallic (or splendent ) minerals have the lustre of polished metal, and with ideal surfaces will work as a reflective surface . Examples include galena , pyrite and magnetite . Pearly minerals consist of thin transparent co-planar sheets. Light reflecting from these layers give them a lustre reminiscent of pearls . Such minerals possess perfect cleavage , with examples including muscovite and stilbite . Resinous minerals have
549-466: A high refractive index (of 1.9 or more). Minerals with a true adamantine lustre are uncommon, with examples including cerussite , zircon , and cubic zirconia . Minerals with a lesser (but still relatively high) degree of lustre are referred to as subadamantine , with some examples being garnet and corundum . Dull (or earthy ) minerals exhibit little to no lustre, due to coarse granulations which scatter light in all directions, approximating
610-482: A process similar to bioleaching . One of the oldest uses of galena was to produce kohl , an eye cosmetic now regarded as toxic due to the risk of lead poisoning . In Ancient Egypt , this was applied around the eyes to reduce the glare of the desert sun and to repel flies, which were a potential source of disease. In pre-Columbian North America, galena was used by indigenous peoples as an ingredient in decorative paints and cosmetics, and widely traded throughout
671-408: A replacement mineral in fossils , but has also been identified in the sclerites of scaly-foot gastropods . Despite being nicknamed "fool's gold", pyrite is sometimes found in association with small quantities of gold. A substantial proportion of the gold is "invisible gold" incorporated into the pyrite (see Carlin-type gold deposit ). It has been suggested that the presence of both gold and arsenic
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#1732786710422732-582: A simple liquid-phase exfoliation route. This is the first study to demonstrate the production of non-layered 2D-platelets from 3D bulk FeS 2 . Furthermore, they have used these 2D-platelets with 20% single walled carbon-nanotube as an anode material in lithium-ion batteries, reaching a capacity of 1000 mAh/g close to the theoretical capacity of FeS 2 . 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. From
793-463: Is cubic and was among the first crystal structures solved by X-ray diffraction . It belongs to the crystallographic space group Pa 3 and is denoted by the Strukturbericht notation C2. Under thermodynamic standard conditions the lattice constant a {\displaystyle a} of stoichiometric iron pyrite FeS 2 amounts to 541.87 pm . The unit cell is composed of
854-429: Is a semiconductor with a small band gap of about 0.4 eV , which found use in early wireless communication systems. It was used as the crystal in crystal radio receivers, in which it was used as a point-contact diode capable of rectifying alternating current to detect the radio signals. The galena crystal was used with a sharp wire, known as a " cat's whisker ", in contact with it. In modern times, galena
915-441: Is a case of coupled substitution but as of 1997 the chemical state of the gold remained controversial. Pyrite gained a brief popularity in the 16th and 17th centuries as a source of ignition in early firearms , most notably the wheellock , where a sample of pyrite was placed against a circular file to strike the sparks needed to fire the gun. Pyrite is used with flintstone and a form of tinder made of stringybark by
976-403: 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. It is found in metamorphic rocks as a product of contact metamorphism . It also forms as a high-temperature hydrothermal mineral , though it occasionally forms at lower temperatures. Pyrite occurs both as a primary mineral, present in
1037-461: Is about 1 atm . A newer commercial use for pyrite is as the cathode material in Energizer brand non-rechargeable lithium metal batteries . Pyrite is a semiconductor material with a band gap of 0.95 eV . Pure pyrite is naturally n-type, in both crystal and thin-film forms, potentially due to sulfur vacancies in the pyrite crystal structure acting as n-dopants. During the early years of
1098-455: Is accelerated by the action of Acidithiobacillus bacteria which oxidize pyrite to first produce ferrous ions ( Fe ), sulfate ions ( SO 4 ), and release protons ( H , or H 3 O ). In a second step, the ferrous ions ( Fe ) are oxidized by O 2 into ferric ions ( Fe ) which hydrolyze also releasing H ions and producing FeO(OH). These oxidation reactions occur more rapidly when pyrite
1159-422: Is accounted for by point symmetry groups C 3 i and C 3 , respectively. The missing center of inversion at S lattice sites has important consequences for the crystallographic and physical properties of iron pyrite. These consequences derive from the crystal electric field active at the sulfur lattice site, which causes a polarization of S ions in the pyrite lattice. The polarisation can be calculated on
1220-491: Is also found in association with sphalerite in low-temperature lead- zinc deposits within limestone beds. Minor amounts are found in contact metamorphic zones, in pegmatites , and disseminated in sedimentary rock. In some deposits, the galena contains up to 0.5% silver , a byproduct that far surpasses the main lead ore in revenue. In these deposits significant amounts of silver occur as included silver sulfide mineral phases or as limited silver in solid solution within
1281-551: Is also the fastest growing in terms of the unroasted iron pyrites imports, with a CAGR of +27.8% from 2007 to 2016. 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. Researchers at Trinity College Dublin , Ireland have demonstrated that FeS 2 can be exfoliated into few-layers just like other two-dimensional layered materials such as graphene by
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#17327867104221342-525: Is brighter yellow with a greenish hue when wet and is softer (3.5–4 on Mohs' scale). Arsenopyrite (FeAsS) is silver white and does not become more yellow when wet. Iron pyrite is unstable when exposed to the oxidizing conditions prevailing at the Earth's surface: iron pyrite in contact with atmospheric oxygen and water, or damp, ultimately decomposes into iron oxyhydroxides ( ferrihydrite , FeO(OH)) and sulfuric acid ( H 2 SO 4 ). This process
1403-443: Is brittle, gold is malleable. Natural gold tends to be anhedral (irregularly shaped without well defined faces), whereas pyrite comes as either cubes or multifaceted crystals with well developed and sharp faces easy to recognise. Well crystallised pyrite crystals are euhedral ( i.e. , with nice faces). Pyrite can often be distinguished by the striations which, in many cases, can be seen on its surface. Chalcopyrite ( CuFeS 2 )
1464-449: Is finely dispersed (framboidal crystals initially formed by sulfate reducing bacteria (SRB) in argillaceous sediments or dust from mining operations). Pyrite oxidation by atmospheric O 2 in the presence of moisture ( H 2 O ) initially produces ferrous ions ( Fe ) and sulfuric acid which dissociates into sulfate ions and protons , leading to acid mine drainage (AMD). An example of acid rock drainage caused by pyrite
1525-506: Is found in hydrothermal deposits emplaced around 1680 million years ago, which have since been heavily metamorphosed. The largest documented crystal of galena is composite cubo-octahedra from the Great Laxey Mine , Isle of Man , measuring 25 cm × 25 cm × 25 cm (10 in × 10 in × 10 in). Galena is the official state mineral of the U.S. states of Kansas, Missouri, and Wisconsin;
1586-457: Is not a formally recognised mineral, and is named after the Peruvian scientist Jose J. Bravo (1874–1928). Pyrite is distinguishable from native gold by its hardness, brittleness and crystal form. Pyrite fractures are very uneven , sometimes conchoidal because it does not cleave along a preferential plane. Native gold nuggets , or glitters, do not break but deform in a ductile way. Pyrite
1647-535: Is responsible for alexandrite's characteristic green to red colour change. Alexandrite from the Ural Mountains in Russia is green by daylight and red by incandescent light. Other varieties of alexandrite may be yellowish or pink in daylight and a columbine or raspberry red by incandescent light. The optimum or "ideal" colour change would be fine emerald green to fine purplish red, but this is rare. Iridescence
1708-430: 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
1769-417: Is the 2015 Gold King Mine waste water spill . Pyrite oxidation is sufficiently exothermic that underground coal mines in high-sulfur coal seams have occasionally had serious problems with spontaneous combustion . The solution is the use of buffer blasting and the use of various sealing or cladding agents to hermetically seal the mined-out areas to exclude oxygen. In modern coal mines, limestone dust
1830-427: Is the 'play' or 'fire' of rainbow-coloured light caused by very thin regular structures or layers beneath the surface of a gemstone. Similar to a thin film of oil on water, these layers interfere with the rays of reflected light, reinforcing some colours and cancelling others. Iridescence is seen at its best in precious opal . Schiller (German, literally "shimmer"), is the metallic iridescence originating from below
1891-432: Is the display of a star-shaped luminous area. It is seen in some sapphires and rubies , where it is caused by impurities of rutile . It can also occur in garnet , diopside and spinel . Aventurescence (or aventurization ) is a reflectance effect like that of glitter . It arises from minute, preferentially oriented mineral platelets within the material. These platelets are so numerous that they also influence
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1952-486: Is the largest known deposit, and in the Driftless Area of Illinois , Iowa and Wisconsin , providing the origin of the name of Galena, Illinois , a historical settlement known for the material. Galena also was a major mineral of the zinc -lead mines of the tri-state district around Joplin in southwestern Missouri and the adjoining areas of Kansas and Oklahoma . Galena is also an important ore mineral in
2013-503: Is the way light interacts with the surface of a crystal , rock , or mineral . The word traces its origins back to the Latin lux , meaning "light", and generally implies radiance, gloss, or brilliance. A range of terms are used to describe lustre, such as earthy , metallic , greasy , and silky . Similarly, the term vitreous (derived from the Latin for glass , vitrum ) refers to
2074-570: Is used to make marcasite jewelry . 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 . At the time when the term became common in jewelry making, "marcasite" referred to all iron sulfides including pyrite, and not to the orthorhombic FeS 2 mineral marcasite which is lighter in color, brittle and chemically unstable, and thus not suitable for jewelry making. Marcasite jewelry does not actually contain
2135-477: The Kaurna people of South Australia , as a traditional method of starting fires. Pyrite has been used since classical times to manufacture copperas ( ferrous sulfate ). Iron pyrite was heaped up and allowed to weather (an example of an early form of heap leaching ). The acidic runoff from the heap was then boiled with iron to produce iron sulfate. In the 15th century, new methods of such leaching began to replace
2196-432: The 20th century, pyrite was used as a mineral detector in radio receivers, and is still used by crystal radio hobbyists. Until the vacuum tube matured, the crystal detector was the most sensitive and dependable detector available—with considerable variation between mineral types and even individual samples within a particular type of mineral. Pyrite detectors occupied a midway point between galena detectors and
2257-603: The Iberian Peninsula. In the beliefs of the Thai people (especially those in the south), pyrite is known as Khao tok Phra Ruang , Khao khon bat Phra Ruang (ข้าวตอกพระร่วง, ข้าวก้นบาตรพระร่วง) or Phet na tang , Hin na tang (เพชรหน้าทั่ง, หินหน้าทั่ง). It is believed to be a sacred item that has the power to prevent evil, black magic or demons. Lustre (mineralogy) Lustre ( British English ) or luster ( American English ; see spelling differences )
2318-1009: The Linares mines in Spain were worked from before the Roman times until the end of the 20th century; the Madan and Rhodope Mountains in Bulgaria ; the Sullivan Mine of British Columbia ; Broken Hill and Mount Isa in Australia ; and the ancient mines of Sardinia . In the United States , it occurs most notably as lead-zinc ore in the Mississippi Valley type deposits of the Lead Belt in southeastern Missouri , which
2379-675: The appearance of resin , chewing gum or (smooth-surfaced) plastic. A principal example is amber , which is a form of fossilized resin. Silky minerals have a parallel arrangement of extremely fine fibres, giving them a lustre reminiscent of silk . Examples include asbestos , ulexite and the satin spar variety of gypsum . A fibrous lustre is similar, but has a coarser texture. Submetallic minerals have similar lustre to metal, but are duller and less reflective. A submetallic lustre often occurs in near-opaque minerals with very high refractive indices, such as sphalerite , cinnabar , anthracite , and cuprite . Vitreous minerals have
2440-450: The arrangement of the metal and diatomic anions differ from that of pyrite. Despite its name, chalcopyrite ( CuFeS 2 ) does not contain dianion pairs, but single S sulfide anions. Pyrite usually forms cuboid crystals, sometimes forming in close association to form raspberry-shaped masses called framboids . However, under certain circumstances, it can form anastomosing filaments or T-shaped crystals. Pyrite can also form shapes almost
2501-425: The basis of higher-order Madelung constants and has to be included in the calculation of the lattice energy by using a generalised Born–Haber cycle . This reflects the fact that the covalent bond in the sulfur pair is inadequately accounted for by a strictly ionic treatment. Arsenopyrite has a related structure with heteroatomic As–S pairs rather than S-S pairs. Marcasite also possesses homoatomic anion pairs, but
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2562-457: The burning of sulfur as a source of sulfuric acid . By the 19th century, it had become the dominant method. Pyrite remains in commercial use for the production of sulfur dioxide , for use in such applications as the paper industry , and in the manufacture of sulfuric acid. 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), p S 2
2623-437: The concrete pores) and gypsum creates inner tensile forces in the concrete matrix which destroy the hardened cement paste, form cracks and fissures in concrete, and can lead to the ultimate ruin of the structure. Normalized tests for construction aggregate certify such materials as free of pyrite or marcasite. Pyrite is the most common of sulfide minerals and is widespread in igneous, metamorphic, and sedimentary rocks. It
2684-545: The eastern United States. Traces of galena are frequently found at the Mississippian city at Kincaid Mounds in present-day Illinois. The galena used at the site originated from deposits in southeastern and central Missouri and the Upper Mississippi Valley. Galena is the primary ore of lead, and is often mined for its silver content. It is used as a source of lead in ceramic glaze . Galena
2745-478: The effect may also occur in other minerals such as aquamarine , moonstone and tourmaline . Colour change is most commonly found in alexandrite, a variety of chrysoberyl gemstones. Other gems also occur in colour-change varieties, including (but not limited to) sapphire , garnet , spinel . Alexandrite displays a colour change dependent upon light, along with strong pleochroism . The gem results from small-scale replacement of aluminium by chromium oxide, which
2806-569: The former mining communities of Galena, Kansas , Galena, Illinois , Galena, South Dakota and Galena, Alaska , take their names from deposits of this mineral. Galena belongs to the octahedral sulfide group of minerals that have metal ions in octahedral positions, such as the iron sulfide pyrrhotite and the nickel arsenide niccolite . The galena group is named after its most common member, with other isometric members that include manganese bearing alabandite and niningerite . Divalent lead (Pb) cations and sulfur (S) anions form
2867-637: The galena structure. These argentiferous galenas have long been an important ore of silver. Silver-bearing galena is almost entirely of hydrothermal origin; galena in lead-zinc deposits contains little silver. Galena deposits are found worldwide in various environments. Noted deposits include those at Freiberg in Saxony ; Cornwall , the Mendips in Somerset , Derbyshire , and Cumberland in England ;
2928-441: The lustre of glass . (The term is derived from the Latin for glass, vitrum .) This type of lustre is one of the most commonly seen, and occurs in transparent or translucent minerals with relatively low refractive indices. Common examples include calcite , quartz , topaz , beryl , tourmaline and fluorite , among others. Waxy minerals have a lustre resembling wax . Examples include jade and chalcedony . Asterism
2989-511: The material's body colour. In aventurine quartz , chrome-bearing fuchsite makes for a green stone and various iron oxides make for a red stone. Chatoyant minerals display luminous bands, which appear to move as the specimen is rotated. Such minerals are composed of parallel fibers (or contain fibrous voids or inclusions), which reflect light into a direction perpendicular to their orientation, thus forming narrow bands of light. The most famous examples are tiger's eye and cymophane , but
3050-419: The mineral marcasite. The specimens of pyrite, when it appears as good quality crystals, are used in decoration. They are also very popular in mineral collecting. Among the sites that provide the best specimens are Soria and La Rioja provinces (Spain). In value terms, China ($ 47 million) constitutes the largest market for imported unroasted iron pyrites worldwide, making up 65% of global imports. China
3111-445: The more mechanically complicated perikon mineral pairs. Pyrite detectors can be as sensitive as a modern 1N34A germanium diode detector. Pyrite has been proposed as an abundant, non-toxic, inexpensive material in low-cost photovoltaic solar panels. Synthetic iron sulfide was used with copper sulfide to create the photovoltaic material. More recent efforts are working toward thin-film solar cells made entirely of pyrite. Pyrite
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#17327867104223172-554: The most abundant and widely distributed sulfide minerals . It crystallizes in the cubic crystal system often showing octahedral forms. It is often associated with the minerals sphalerite , calcite and fluorite . Galena is the main ore of lead , used since ancient times, since lead can be smelted from galena in an ordinary wood fire. Galena typically is found in hydrothermal veins in association with sphalerite , marcasite , chalcopyrite , cerussite , anglesite , dolomite , calcite , quartz , barite , and fluorite . It
3233-660: The original sediments, and as a secondary mineral, deposited during diagenesis . Pyrite and marcasite commonly occur as replacement pseudomorphs after fossils in black shale and other sedimentary rocks formed under reducing environmental conditions. Pyrite is common as an accessory mineral in shale, where it is formed by precipitation from anoxic seawater, and coal beds often contain significant pyrite. Notable deposits are found as lenticular masses in Virginia, U.S., and in smaller quantities in many other locations. Large deposits are mined at Rio Tinto in Spain and elsewhere in
3294-438: The oxidation state of molybdenum is Mo. The mineral arsenopyrite has the formula Fe As S. Whereas pyrite has [S 2 ] units, arsenopyrite has [AsS] units, formally derived from deprotonation of arsenothiol (H 2 AsSH). Analysis of classical oxidation states would recommend the description of arsenopyrite as Fe[AsS]. Iron-pyrite FeS 2 represents the prototype compound of the crystallographic pyrite structure. The structure
3355-523: The perspective of classical inorganic chemistry , which assigns formal oxidation states to each atom, pyrite and marcasite are probably best described as Fe[S 2 ]. This formalism recognizes that the sulfur atoms in pyrite occur in pairs with clear S–S bonds. These persulfide [S–S] units can be viewed as derived from hydrogen disulfide , H 2 S 2 . Thus pyrite would be more descriptively called iron persulfide, not iron disulfide. In contrast, molybdenite , Mo S 2 , features isolated sulfide S centers and
3416-680: The pyrite structure. The Fe atoms are bonded to six S atoms, giving a distorted octahedron. The material is a semiconductor . The Fe ions is usually considered to be low spin divalent state (as shown by Mössbauer spectroscopy as well as XPS). The material as a whole behaves as a Van Vleck paramagnet , despite its low-spin divalency. The sulfur centers occur in pairs, described as S 2 . Reduction of pyrite with potassium gives potassium dithioferrate , KFeS 2 . This material features ferric ions and isolated sulfide (S) centers. The S atoms are tetrahedral, being bonded to three Fe centers and one other S atom. The site symmetry at Fe and S positions
3477-578: The rock and lead eventually to roof fall . Building stone containing pyrite tends to stain brown as pyrite oxidizes. This problem appears to be significantly worse if any marcasite is present. The presence of pyrite in the aggregate used to make concrete can lead to severe deterioration as pyrite oxidizes. 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 ( H 2 S ). These problems included
3538-560: 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. Cattierite ( Co S 2 ), vaesite ( Ni S 2 ) and hauerite ( Mn S 2 ), as well as sperrylite ( Pt As 2 ) are similar in their structure and belong also to the pyrite group. Bravoite is a nickel-cobalt bearing variety of pyrite, with > 50% substitution of Ni for Fe within pyrite. Bravoite
3599-561: The silver mining regions of Colorado , Idaho , Utah and Montana . Of the latter, the Coeur d'Alene district of northern Idaho was most prominent. Australia is the world's leading producer of lead as of 2021, most of which is extracted as galena. Argentiferous galena was accidentally discovered at Glen Osmond in 1841, and additional deposits were discovered near Broken Hill in 1876 and at Mount Isa in 1923. Most galena in Australia
3660-402: The surface of a stone that occurs when light is reflected between layers of minerals. It is seen in moonstone and labradorite and is very similar to adularescence and aventurescence . Galena Galena , also called lead glance , is the natural mineral form of lead(II) sulfide (PbS). It is the most important ore of lead and an important source of silver . Galena is one of
3721-548: 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. By Georgius Agricola 's time, c. 1550 , the term had become a generic term for all of the sulfide minerals . Pyrite is usually found associated with other sulfides or oxides in quartz veins , sedimentary rock , and metamorphic rock , as well as in coal beds and as
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