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| {{Redirect|Fool's Gold}}
| | == sagte Belash und bemerkte Nike Air Jordan Schweiz == |
| {{About|iron pyrite|other pyrite minerals|Pyrite group}}
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| {{Infobox mineral
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| | name = Pyrite
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| | category = [[Sulfide mineral]]
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| | boxbgcolor =
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| | image = 2780M-pyrite1.jpg
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| | imagesize =
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| | caption = Pyrite cubic crystals on [[marl]] from Navajún, Rioja, Spain (size: {{convert|95|by|78|mm}}, {{convert|512|g}}; main crystal: {{convert|31|mm}} on edge)
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| | formula = FeS<sub>2</sub>
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| | strunz = 02.EB.05a
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| | dana = 2.12.1.1
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| | symmetry = Isometric diploidal<br />[[Space group]]: Pa{{overline|3}} <br />[[H-M symbol]]: 2/m{{overline|3}}
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| | unit cell = a = 5.417 [[Ångstrom|Å]], Z=4
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| | molweight = 119.98 g/mol
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| | color = Pale brass-yellow reflective; tarnishes darker and iridescent
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| | habit = Cubic, faces may be striated, but also frequently octahedral and pyritohedron. Often inter-grown, massive, radiated, granular, globular, and stalactitic.
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| | system = [[Cubic (crystal system)|Isometric]]
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| | twinning = Penetration and contact twinning
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| | cleavage = Indistinct on {001}; partings on {011} and {111}
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| | fracture = Very uneven, sometimes conchoidal
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| | tenacity = Brittle
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| | mohs = 6–6.5
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| | luster = Metallic, glistening
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| | refractive =
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| | opticalprop =
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| | birefringence =
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| | pleochroism =
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| | streak = Greenish-black to brownish-black
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| | gravity = 4.95–5.10
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| | density = 4.8–5 g/cm<sup>3</sup>
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| | melt =
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| | fusibility = 2.5–3 to a magnetic globule
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| | diagnostic =
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| | solubility = Insoluble in water
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| | diaphaneity = Opaque
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| | other = [[paramagnetism|paramagnetic]]
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| | references = <ref name=Hurlbut>Hurlbut, Cornelius S.; Klein, Cornelis, 1985, ''Manual of Mineralogy'', 20th ed., John Wiley and Sons, New York, pp 285–286, ISBN 0-471-80580-7</ref><ref>[http://webmineral.com/data/Pyrite.shtml Pyrite on webmineral]. Webmineral.com. Retrieved on 2011-05-25.</ref><ref>[http://www.mindat.org/min-3314.html Pyrite on]. Mindat.org. Retrieved on 2011-05-25.</ref><ref>[http://rruff.geo.arizona.edu/doclib/hom/pyrite.pdf Handbook of Mineralogy]. (PDF) . Retrieved on 2011-05-25.</ref>
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| }}
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| The [[mineral]] '''pyrite''', or '''iron pyrite''', also known as '''fool's gold''', is an iron [[sulfide]] with the [[chemical formula|formula]] [[iron|Fe]][[sulfur|S]]<sub>2</sub>. This mineral's metallic [[Luster (mineralogy)|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]].<ref>Julia A. Jackson, James Mehl and Klaus Neuendorf, [http://books.google.com/books?id=SfnSesBc-RgC&lpg=PA82&pg=PA82 Glossary of Geology], American Geological Institute (2005) p. 82.</ref><ref>Albert H. Fay, [http://books.google.com/books?id=fB4bAAAAYAAJ&pg=PA103 A Glossary of the Mining and Mineral Industry], United States Bureau of Mines (1920) pp. 103–104.</ref>
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| Pyrite is the most common of the [[sulfide mineral]]s. The name pyrite is derived from the [[Greek language|Greek]] πυρίτης (''puritēs''), "of fire" or "in fire",<ref>[http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3Dpuri%2Fths1 πυρίτης], Henry George Liddell, Robert Scott, ''A Greek-English Lexicon'', on Perseus</ref> in turn from πύρ (''pur''), "fire".<ref>[http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3Dpu%3Dr πύρ], Henry George Liddell, Robert Scott, ''A Greek-English Lexicon'', on Perseus</ref> 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 we now call pyrite.<ref>James Dwight Dana, Edward Salisbury Dana, [http://books.google.com/books?id=lHS7AAAAIAAJ&pg=PA86 Descriptive Mineralogy, 6th Ed.], Wiley, New York (1911) p. 86.</ref>
| | Das Leben war nicht einfach, auch in der größten Haus in der Stadt. Dezember bis Februar, es war der einzige Raum mit Wärme, sagte Belash und bemerkte, dass Brennholz knapp war. Also, ich an einen anderen Freund, der $ 50 hat zu gehen und leihen die $ 50 Dollar zu gehen, kaufen die Dope. Ich gehe kaufen die Dope für 50 $ zu wissen, dass ich bald verkaufen sie an meinen Freund für $ 100 und ich werde 50 $ in den Deal gemacht haben. <br><br>BeesNeez Erzählung Studio, Geometrie Erzählung Studio mit Jahren [http://www.balmer-bd.ch/demo/cache.html Nike Air Jordan Schweiz] der wiederkehr auf den Fernen Nordküste von New South Wales. Mathe-Lektion 5. Verzeichnis der Free Knitting Patterns Online. Anfänger Strickanleitung, Tipps, Tricks, Testimonials, Links und vieles mehr. <br><br>Wurden zunächst bewusst das Video von einem Tippgeber, der uns mit dem Eigentümer des Video angeschlossen, nachdem wir nach Toronto gemacht, schrieb Cook. In relativ konstante Kommunikation mit dem Tippgeber seitdem. Wenn du ihm den Kopf geben am gleichen Ort zur gleichen Zeit in der gleichen Weise, wenn irgendwann wird [http://www.latinmusicshop.ch/database/upload.php Longchamp Le Pliage] es ein bisschen langweilig. So sicher sein, von Zeit zu Zeit zu experimentieren und die Position. <br><br>Gestern machten wir uns entschlossen, unsere eigene Kleiderformen für die Etsy Labs machen und dachten, dass wir die Liebe mit euch zu teilen, wenn Sie zu einem machen wollen. 19. Die They Killed Kenny Wieder Trope als in der populären Kultur verwendet wird, mit einer Liste [http://www.htmi.ch/InfoBack/HaodeUpload/Filer.aspx Polo Ralph Lauren Schweiz] von Beispielen aus allen Medien. Gleiche alte Lied (informal) pflegte zu sagen, dass eine Situation oder jemand das Verhalten gleich bleibt, vor allem wenn es langweilig oder ärgerlich ist "Wie die Arbeit gehen? "Oh. <br><br>Unterlassen Nagellackentferner mit Aceton und nehmen Sie Nagellack höchstens einmal pro Woche. Sie können immer Ihre Nägel während der Woche, wenn Ihre Nagellack-Chips. Leider ist meine Begeisterung wurde bald durch meine Unfähigkeit, um E-Mail-Konten gemildert. Nach verbrachte ich eine gute Stunde oder so, daran zu arbeiten gab es auf. <br><br>Über Bremen Castings Inc.: Besitz dieser Familie Gießerei und Maschinenhalle wurde 1939 in Bremen, Indiana gegründet. Mit über 70 Jahren Erfahrung, ist BCI weltweit für seine Qualität Grau-und Sphäroguss bearbeitet Gussteile bekannt. Sprechen Sie mit Ihrem Kind nicht zu ihm auf. Beim Gespräch mit Ihrem Kind, einwerfen, einige seiner highrolling Emotionen in das Gespräch zwischen den beiden von Ihnen. <br><br>Diese liebenswerte Kuriositäten Dinge tun, normale Linsen nur aboutlike [http://www.latinmusicshop.ch/config/router.php Nike Air Max 90] Biege träumen. Tipp sie so oder so, und plötzlich das Bild hat eine seltsame, schöne, softfocus Look mit nur ein bisschen scharf. Ich bin 21. Ich habe immer Behandlung und derzeit 100 mg zoloft.<ul> |
| By [[Georgius Agricola]]'s time, the term had become a generic term for all of the [[Pyrite group|sulfide minerals]].<ref>[[Herbert Clark Hoover]] and [[Lou Henry Hoover]], translators of [[Georgius Agricola]], [De Re Metallica], The Mining Magazine, London (1912; Dover reprint, 1950); see footnote, p. 112.</ref>
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| | | <li>[http://demon-inferno.net/forum/viewtopic.php?f=10&t=258303 http://demon-inferno.net/forum/viewtopic.php?f=10&t=258303]</li> |
| Pyrite is usually found associated with other sulfides or [[oxide]]s in [[quartz]] [[Vein (geology)|veins]], [[sedimentary rock]], and [[metamorphic rock]], as well as in [[coal]] beds and as a replacement mineral in [[fossil]]s. Despite being nicknamed fool's gold, pyrite is sometimes found in association with small quantities of [[gold]]. Gold and [[arsenic]] occur as a coupled substitution in the pyrite structure. In the [[Carlin–type gold deposit]]s, arsenian pyrite contains up to 0.37 wt% gold.<ref>M. E. Fleet and A. Hamid Mumin, [http://www.minsocam.org/msa/AmMin/toc/Articles_Free/1997/Fleet_p182-193_97.pdf Gold-bearing arsenian pyrite and marcasite and arsenopyrite from Carlin Trend gold deposits and laboratory synthesis], American Mineralogist 82 (1997) pp. 182–193</ref>
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| | | <li>[http://showtime2.no-ip.info/forum-php/forum/thread.php?threadid=228763&sid= http://showtime2.no-ip.info/forum-php/forum/thread.php?threadid=228763&sid=]</li> |
| ==Uses==
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| [[File:Pyrite from Ampliación a Victoria Mine, Navajún, La Rioja, Spain 2.jpg|thumb|left|Pyrite from Ampliación a Victoria Mine, Navajún, La Rioja, Spain]]
| | <li>[http://zhaigounet.com/news/html/?46029.html http://zhaigounet.com/news/html/?46029.html]</li> |
| Pyrite enjoyed brief popularity in the 16th and 17th centuries as a source of [[Combustion|ignition]] in early [[firearm]]s, 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.{{cn|date=January 2014}}
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| | | <li>[http://enseignement-lsf.com/spip.php?article64#forum18281168 http://enseignement-lsf.com/spip.php?article64#forum18281168]</li> |
| Pyrite has been used since classical times to manufacture ''copperas'', that is, [[iron(II) 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, such leaching began to replace the burning of sulfur as a source of [[sulfuric acid]]. By the 19th century, it had become the dominant method.<ref>{{cite journal |title=Industrial England in the Middle of the Eighteenth Century |journal=Nature |volume=83 |issue=2113 |date=1910-04-28 |pages=264–268 |url=http://www.nature.com/nature/journal/v83/n2113/abs/083264a0.html |doi=10.1038/083264a0|bibcode = 1910Natur..83..264. }}</ref>
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| | | </ul> |
| 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 {{nowrap|550 °C}}; at around {{nowrap|700 °C}} p<sub>S<sub>2</sub></sub> is about {{nowrap|1 atm}}.<ref>{{cite book |title=Principles of extractive metallurgy |author=Terkel Rosenqvist |edition=2nd |publisher=Tapir Academic Press |year=2004 |isbn=82-519-1922-3 |page=52 |url=http://books.google.com/?id=I2mg2ine4AEC&pg=PA52&lpg=PA52&dq=pyrite+%22decomposition+temperature%22&q=pyrite%20%22decomposition%20temperature%22 }}</ref>
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| A newer commercial use for pyrite is as the [[cathode]] material in [[Energizer]] brand non-rechargeable [[lithium battery|lithium batteries]].<ref>Energizer Corporation, [http://data.energizer.com/PDFs/lithiuml91l92_appman.pdf Lithium Iron Disulfide]</ref>
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| Pyrite is a [[semiconductor material]] with a [[band gap]] of 0.95 [[Electronvolt|eV]].<ref>{{cite journal |url=http://www.esqsec.unibe.ch/%5Cpub%5Cpub_51.htm |title=Iron Disulfide (Pyrite) as Photovoltaic Material: Problems and Opportunities |author=K. Ellmer and H. Tributsch |journal=Proceedings of the 12th Workshop on Quantum Solar Energy Conversion – (QUANTSOL 2000) |date=2000-03-11}}</ref>
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| During the early years of the 20th century, pyrite was used as a [[Cat's-whisker detector|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 (radio)|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 the more mechanically complicated [[Cat's-whisker detector#Types|perikon]] mineral pairs. Pyrite detectors can be as sensitive as a modern 1N34A [[diode]] detector.<ref>[http://books.google.com/books?id=eSguAAAAYAAJ&pg=PA302 The Principles Underlying Radio Communication, Radio Pamphlet No. 40], U.S. Army Signal Corps, Dec. 10 (1918) section 179, pp. 302–305.</ref><ref>Thomas H. Lee, [http://books.google.com/books?id=DzcMK-2mFQUC&lpg=PA4&pg=PA4 The Design of Radio Frequency Integrated Circuits, 2nd Ed.], Cambridge University Press (2004) pp. 4–6.</ref>
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| Pyrite has been proposed as an abundant, inexpensive material in low cost [[photovoltaic]] solar panels.<ref>{{cite journal |title=Materials Availability Expands the Opportunity for Large-Scale Photovoltaics Deployment |year=2009 |last1=Wadia |first1=Cyrus |last2=Alivisatos |first2=A. Paul |last3=Kammen |first3=Daniel M. |journal=Environmental Science & Technology |volume=43 |issue=6 |page=2072 |doi=10.1021/es8019534|bibcode = 2009EnST...43.2072W }}</ref> Synthetic iron sulfide is used with copper sulfide to create the experimental photovoltaic material.<ref>[http://www.berkeley.edu/news/media/releases/2009/02/17_solar.shtml Cheaper materials could be key to low-cost solar cells] by Robert Sanders, 17 February 2009</ref>
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| Pyrite is used to make [[marcasite jewelry]]. Marcasite jewelry, made from small faceted pieces of pyrite, often set in silver, was popular in the [[Victorian era]].<ref>{{cite book
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| |last = Hesse
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| |first = Rayner W.
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| |title = Jewelrymaking Through History: An Encyclopedia
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| |publisher = [[Greenwood Publishing Group]]
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| |year = 2007
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| |location =
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| |page = 15
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| |url = http://books.google.com/?id=IVgU0icm948C&pg=PA15
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| |isbn =0-313-33507-9}}
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| </ref> | |
| [[Marcasite jewelry]] does not contain [[marcasite]], which is a medieval term that encompassed both pyrite and the mineral now called [[marcasite]].
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| ==Formal oxidation states for pyrite, marcasite, and arsenopyrite==
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| From the perspective of classical inorganic chemistry, which assigns formal oxidation states to each atom, pyrite is probably best described as Fe<sup>2+</sup>S<sub>2</sub><sup>2−</sup>. This formalism recognizes that the sulfur atoms in pyrite occur in pairs with clear S–S bonds. These persulfide units can be viewed as derived from [[hydrogen disulfide]], H<sub>2</sub>S<sub>2</sub>. Thus pyrite would be more descriptively called iron persulfide, not iron disulfide. In contrast, [[molybdenite]], [[molybdenum|Mo]]S<sub>2</sub>, features isolated sulfide ({{chem|S|2-}}) centers because the oxidation state of molybdenum is Mo<sup>4+</sup>. The mineral arsenopyrite has the formula Fe[[arsenic|As]]S. Whereas pyrite has S<sub>2</sub> subunits, arsenopyrite has AsS units, formally derived from [[deprotonation]] of H<sub>2</sub>AsSH. Analysis of classical oxidation states would recommend the description of arsenopyrite as {{chem|Fe|3+|(AsS)|3-}}.<ref name=Vaughan>Vaughan, D. J.; Craig, J. R. "Mineral Chemistry of Metal Sulfides" Cambridge University Press, Cambridge (1978) ISBN 0-521-21489-0</ref>
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| ==Crystallography==
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| [[Image:FeS2structure.png|thumb|right|Crystal structure of pyrite. In the center of the cell a S<sub>2</sub><sup>2-</sup> pair is seen in yellow.]]
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| Iron-pyrite FeS<sub>2</sub> represents the prototype compound of the crystallographic pyrite structure. The structure is simple [[cubic crystal system|cubic]] and was among the first [[crystal structures]] solved by [[X-ray diffraction]].<ref name=Brag1913>{{cite journal |author = W. L. Bragg |title = The structure of some crystals as indicated by their diffraction of X-rays |url=http://www.jstor.org/stable/93488 |journal = [[Proceedings of the Royal Society A]] |volume = 89 |pages = 248–277 |year = 1913 |doi = 10.1098/rspa.1913.0083 |bibcode = 1913RSPSA..89..248B |issue = 610 }}</ref> It belongs to the crystallographic [[space group]] ''Pa''{{overline|3}} and is denoted by the [[Zeitschrift für Kristallographie|Strukturbericht]] notation C2. Under thermodynamic standard conditions the [[lattice constant]] <math>a</math> of stoichiometric iron pyrite FeS<sub>2</sub> amounts to {{nowrap|541.87 pm}}.<ref name=Birk1991>{{cite journal|author = M. Birkholz, S. Fiechter, A. Hartmann, and H. Tributsch|title = Sulfur deficiency in iron pyrite (FeS<sub>2-x</sub>) and its consequences for band structure models|journal = Phys. Rev. B|volume = 43|page = 11926|year = 1991|doi = 10.1103/PhysRevB.43.11926|bibcode = 1991PhRvB..4311926B|issue = 14 }}</ref> The [[cubic crystal system#unit cell|unit cell]] is composed of a Fe [[Bravais lattice|face-centered cubic sublattice]] into which the S ions are embedded. The pyrite structure is also taken by other compounds ''MX''<sub>2</sub> of [[transition metals]] ''M'' and [[chalcogen]]s ''X'' = [[oxygen|O]], [[sulfur|S]], [[selenium|Se]] and [[tellurium|Te]]. Also certain [[pnictide|dipnictides]] with ''X'' standing for [[phosphorus|P]], [[arsenic|As]] and [[antimony|Sb]] etc. are known to adopt the pyrite structure.<ref name=Bres1994>{{cite journal|author = N. E. Brese, and H. G. von Schnering|title = Bonding Trends in Pyrites and a Reinvestigation of the Structure of PdAs<sub>2</sub>, PdSb<sub>2</sub>, PtSb<sub>2</sub> and PtBi<sub>2</sub>|journal = Z. Anorg. Allg. Chem.|volume = 620|page = 393|year = 1994|doi = 10.1002/zaac.19946200302|issue = 3}}</ref>
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| In the first bonding sphere, the Fe atoms are surrounded by six S nearest neighbours, in a distorted octahedral arrangement. The material is a [[diamagnetic]] [[semiconductor]] and the Fe ions should be considered to be in a ''[[low spin]]'' [[divalent]] state (as shown by [[Mössbauer spectroscopy]] as well as XPS), rather than a [[tetravalent]] state as the stoichiometry would suggest.
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| The positions of ''X'' ions in the pyrite structure may be derived from the [[fluorite]] structure, starting from a hypothetical Fe<sup>2+</sup>(S<sup>-</sup>)<sub>2</sub> structure. Whereas [[fluorine|F]]<sup>-</sup> ions in CaF<sub>2</sub> occupy the centre positions of the eight subcubes of the cubic unit cell (¼ ¼ ¼) etc., the S<sup>-</sup> ions in FeS<sub>2</sub> are shifted from these high symmetry positions along <111> axes to reside on (''uuu'') and symmetry-equivalent positions. Here, the parameter ''u'' should be regarded as a free atomic parameter that takes different values in different pyrite-structure compounds (iron pyrite FeS<sub>2</sub>: ''u''(S) = 0.385 <ref name=Stev1980>{{cite journal|author = E. D. Stevens, M. L. de Lucia, and P. Coppens|title = Experimental observation of the Effect of Crystal Field Splitting on the Electron Density Distribution of Iron Pyrite|journal = Inorg. Chem.|volume = 19|page = 813|year = 1980|doi = 10.1021/ic50206a006|issue = 4}}</ref>). The shift from fluorite u=0.25 to pyrite u=0.385 is rather large and creates a S-S distance that is clearly a binding one. This is not surprising as in contrast to F<sup>-</sup> an ion S<sup>-</sup> is not a closed shell species. It is isoelectronic with a chlorine ''atom'', also undergoing pairing to form Cl<sub>2</sub> molecules. Both low spin Fe<sup>2+</sup> and the disulfide S<sub>2</sub><sup>2-</sup> moeties are closed shell entities, explaining the diamagnetic en semiconducting properties.
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| The S atoms have bonds with three Fe and one other S atom. The site symmetry at Fe and S positions is accounted for by [[crystallographic point group|point symmetry groups]] ''C''<sub>3''i''</sub> and ''C''<sub>3</sub>, respectively. The missing [[centrosymmetry|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 [[dipole#Atomic dipoles|polarisation]] of S ions in the pyrite lattice.<ref name= BJPC1992>{{cite journal|author = M. Birkholz|url = http://www.mariobirkholz.de/JPhysC1992.pdf|title = The crystal energy of pyrite|journal = J. Phys.: Condens. Matt.|volume = 4|page = 6227|year = 1992|doi = 10.1088/0953-8984/4/29/007|bibcode=1992JPCM....4.6227B|issue = 29}}</ref> The polarisation can be calculated on the basis of higher-order [[Madelung constant]]s 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 ill accounted for in the strictly ionic treatment of Madelung theory.
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| Arsenopyrite has a related structure with heteroatomic As-S pairs rather than homoatomic ones. Marcasite also possesses homoatomic anion pairs, but the arrangement of the metal and diatomic anions is different than in a pyrite. Despite its name a chalcopyrite does not contain dianion pairs, but single S<sup>2-</sup> sulfide anions.
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| == Crystal habit == | |
| [[File:Pyrite elbe.jpg|thumb|right|[[Dodecahedron]]- shaped crystals from Italy]]
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| Pyrite usually forms cuboid crystals, sometimes forming in close association to form raspberry-like [[framboid]]s. However, under certain circumstances, it can form [[Anastomosis|anastamozing]] filaments or T-shaped crystals.<ref name="Bonev2005">{{cite doi|10.1127/0935-1221/2005/0017-0905}}</ref>
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| Pyrite can also form [[dodecahedron|dodecahedral]] crystals and this suggests an explanation for the artificial geometrical models found in Europe as early as the 5th century BC.<ref>Dana J. et al.,(1944), ''System of mineralogy'', New York, p 282</ref>
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| ==Varieties== | |
| [[Cattierite]] ([[Cobalt|Co]][[sulfur|S]]<sub>2</sub>) and [[vaesite]] ([[Nickel|Ni]][[sulfur|S]]<sub>2</sub>) are similar in their structure and belong also to the pyrite group.
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| Bravoite is a nickel-cobalt bearing variety of pyrite, with >50% substitution of [[nickel|Ni]]<sup>2+</sup> for Fe<sup>2+</sup> within pyrite. Bravoite is not a formally recognised mineral, and is named after Peruvian scientist Jose J. Bravo (1874–1928).<ref>[http://www.mindat.org/min-759.html Mindat – bravoite]. Mindat.org (2011-05-18). Retrieved on 2011-05-25.</ref>
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| ==Distinguishing similar minerals==
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| 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. [[Chalcopyrite]] is brighter yellow with a greenish hue when wet and is softer (3.5–4 on Mohs' scale).<ref>[http://www.minerals.net/mineral/sulfides/pyrite/pyrite.htm Pyrite on]. Minerals.net (2011-02-23). Retrieved on 2011-05-25.</ref> [[Arsenopyrite]] is silver white and does not become more yellow when wet.
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| ==Hazards==
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| [[File:GoldinPyriteDrainage acide.JPG|thumb|A pyrite cube (center) has dissolved away from a host rock, leaving behind trace gold.]]
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| 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]]. This process is hastened by the action of ''[[Acidithiobacillus]]'' bacteria which oxidize the pyrite to produce ferrous iron 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.
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| ===Acid drainage===
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| [[Sulfate]] released from decomposing pyrite combines with water, producing [[sulfuric acid]], leading to [[acid rock drainage]] and potentially [[acid rain]].
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| ===Dust explosions===
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| Pyrite oxidation is sufficiently [[exothermic]] that underground [[coal mine]]s in high-sulfur coal seams have occasionally had serious problems with [[spontaneous combustion]] in the mined-out areas of the mine. The solution is to [[Hermetic seal|hermetically seal]] the mined-out areas to exclude oxygen.<ref>Andrew Roy, Coal Mining in Iowa, ''Coal Trade Journal'', quoted in [http://books.google.com/books?id=nH0UAAAAYAAJ&lpg=PA609&pg=PA613 History of Lucas County Iowa], State Historical Company, Des Moines (1881) pp. 613–615.</ref>
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| In modern coal mines, [[limestone]] dust is sprayed onto the exposed coal surfaces to reduce the hazard of [[dust explosion]]s. 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]] [[sulfate]]s formed may exert crystallization pressure that can expand cracks in the rock and lead eventually to [[cave-in|roof fall]].<ref>{{cite journal |doi=10.1016/j.coal.2005.03.013 |title=Colliery and surface hazards through coal-pyrite oxidation (Pennsylvanian Sydney Coalfield, Nova Scotia, Canada) |year=2005 |last1=Zodrow |first1=E |journal=International Journal of Coal Geology |volume=64 |page=145}}</ref>
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| ===Weakened building materials===
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| Building stone containing pyrite tends to stain brown as the pyrite oxidizes. This problem appears to be significantly worse if any [[marcasite]] is present.<ref>Oliver Bowles, [http://books.google.com/books?id=OksMAAAAYAAJ&lpg=PA25&pg=PA25 The Structural and Ornamental Stones of Minnesota, Bulletin 663], United States Geological Survey, Washington (1918) p. 25.</ref> The presence of pyrite in the [[Construction aggregate|aggregate]] used to make [[concrete]] can lead to severe deterioration as the pyrite oxidizes.<ref>{{cite journal|doi=10.1016/j.cemconres.2004.06.030|title=Internal deterioration of concrete by the oxidation of pyrrhotitic aggregates|year=2005 |last1=Tagnithamou|first1=A|last2=Sariccoric|first2=M |last3=Rivard|first3=P |journal=Cement and Concrete Research|volume=35|page=99}}</ref> In early 2009, problems with [[Chinese drywall]] imported into the [[United States]] after [[Hurricane Katrina]] were attributed to oxidation of pyrite.<ref>William Angelo, [http://enr.construction.com/business_management/safety_health/2009/0128-ChineseDrywallCorrosion.asp A Material Odor Mystery Over Foul-Smelling Drywall], from the web site of [http://enr.construction.com/ Engineering News Record Construction], dated 1/28/2009.</ref> In the United States, in Canada,<ref>"[http://www.consommateur.qc.ca/acqc/PyriHouse.pdf PYRITE and Your House, What Home-Owners Should Know]" – ISBN 2-922677-01-X - Legal deposit – National Library of Canada, May 2000</ref> and more recently in Ireland,<ref>The Irish Times – Saturday, June 11, 2011 – [http://www.irishtimes.com/newspaper/ireland/2011/0611/1224298735366.html Homeowners in protest over pyrite damage to houses]</ref> pyrite contamination has caused major structural damage. Modern tests for aggregate materials<ref>I.S. EN 13242:2002 Aggregates for unbound and hydraulically bound materials for use in civil engineering work and road construction</ref> certify such materials as free of pyrite.
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| ==Pyritised fossils==
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| [[Image:Bullypyrite.jpg|thumb|left|As a replacement mineral in an [[ammonite]] from France]]
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| Pyrite and [[marcasite]] commonly occur as replacement [[pseudomorph]]s after [[fossils]] in [[black shale]] and other [[sedimentary rocks]] formed under [[Redox|reducing]] environmental conditions.
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| [[Image:Pyrite - disc.jpg|thumb|Disc or "pyrite dollar" from south of [[Tucson, Arizona]]; diameter 10 cm]]
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| However, ''pyrite dollars'' or ''pyrite suns'' which have an appearance similar to [[sand dollar]]s are [[pseudofossil]]s and lack the [[pentagonal]] symmetry of the animal.
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| {{clear}}
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| ==References==
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| {{reflist|30em}}
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| | |
| ==Further reading==
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| * American Geological Institute, 2003, ''Dictionary of Mining, Mineral, and Related Terms'', 2nd ed., Springer, New York, ISBN 978-3-540-01271-9
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| * [http://mineral.galleries.com/minerals/sulfides/pyrite/pyrite.htm Mineral galleries]
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| | |
| ==External links==
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| {{Commons category|Pyrite}}
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| * [http://www.geo.uw.edu.pl/ZASOBY/PYRITE/pyrite6.htm How Minerals Form and Change] "Pyrite oxidation under room conditions".
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| * {{cite web|last=Poliakoff|first=Martyn|title=Fool's Gold|url=http://www.periodicvideos.com/videos/feature_fools_gold.htm|work=[[The Periodic Table of Videos]]|publisher=[[University of Nottingham]]|authorlink=Martyn Poliakoff|year=2009}}
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| [[Category:Pyrite group]]
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| [[Category:Sulfide minerals]]
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| [[Category:Iron minerals]]
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| [[Category:Alchemical substances]]
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| [[Category:Firelighting]]
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| [[Category:Semiconductor materials]]
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| [[Category:Cubic minerals]]
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