Editing Mineral (section)

==Definitions==

===International Mineralogical Association===
The [[International Mineralogical Association]] has established the following requirements for a substance to be considered a distinct mineral:<ref name=nick1998>E. H. Nickel & J. D. Grice (1998): "The IMA Commission on New Minerals and Mineral Names: procedures and guidelines on mineral nomenclature". ''Mineralogy and Petrology'', volume 64, issue 1, pages 237–263. {{doi|10.1007/BF01226571}}</ref><ref name=Nickel>{{cite journal |last = Nickel |first = Ernest H. |title = The definition of a mineral |journal = The Canadian Mineralogist |volume = 33 |issue = 3 |pages = 689–90 |date = 1995 |url = https://pubs.geoscienceworld.org/canmin/article-abstract/33/3/689/12679/the-definition-of-a-mineral?redirectedFrom=fulltext |access-date = 2018-04-04 |archive-date = 2018-08-25 |archive-url = https://web.archive.org/web/20180825002651/https://pubs.geoscienceworld.org/canmin/article-abstract/33/3/689/12679/the-definition-of-a-mineral?redirectedFrom=fulltext |url-status = live }}</ref>

# ''It must be a naturally occurring substance formed by natural geological processes'', on Earth or other extraterrestrial bodies.  This excludes compounds directly and exclusively generated by human activities ([[wikt:anthropogenic|anthropogenic]]) or in living beings ([[wikt:biogenic|biogenic]]), such as [[tungsten carbide]], [[kidney stone disease|urinary calculi]], [[calcium oxalate]] crystals in plant tissues, and [[seashell]]s.  However, substances with such origins may qualify if geological processes were involved in their genesis (as is the case of [[evenkite]], derived from plant material; or [[taranakite]], from [[bat guano]]; or [[alpersite]], from mine tailings).<ref name=Nickel /> Hypothetical substances are also excluded, even if they are predicted to occur in inaccessible natural environments like the Earth's core or other planets.
# ''It must be a solid substance in its natural occurrence.''  A major exception to this rule is native [[mercury (element)|mercury]]: it is still classified as a mineral by the IMA, even though crystallizes only below −39&nbsp;°C, because it was included before the current rules were established.<ref>{{cite web |url=https://www.mindat.org/min-2647.html |title=Mercury |publisher=Mindat.org |access-date=3 April 2018 |archive-date=7 January 2018 |archive-url=https://web.archive.org/web/20180107110532/https://www.mindat.org/min-2647.html |url-status=live }}</ref>  Water and [[carbon dioxide]] are not considered minerals, even though they are often found as [[inclusion (mineral)|inclusions]] in other minerals; but [[Ice|water ice]] is considered a mineral.<ref>{{cite web |url=https://www.mindat.org/min-2001.html |title=Ice |publisher=Mindat.org |access-date=3 April 2018 |archive-date=4 June 2020 |archive-url=https://web.archive.org/web/20200604131947/https://www.mindat.org/min-2001.html |url-status=live }}</ref>
# ''It must have  a well-defined crystallographic structure''; or, more generally, an ordered atomic arrangement.<ref name="DG2_4" /> This property implies several [[macroscopic scale|macroscopic]] physical properties, such as crystal form, hardness, and cleavage.<ref name="CL13-14">{{harvnb|Chesterman|Lowe|2008}}, pp. 13–14</ref> It excludes [[ozokerite]], [[limonite]], [[obsidian]] and many other amorphous (non-crystalline) materials that occur in geologic contexts.
# ''It must have a fairly well defined chemical composition''. However, certain crystalline substances with a fixed structure but variable composition may be considered single mineral species.  A common class of examples are [[solid solution]]s such as [[mackinawite]], (Fe, Ni)<sub>9</sub>S<sub>8</sub>, which is mostly a [[iron|ferrous]] sulfide with a significant fraction of iron atoms replaced by [[nickel]] atoms.<ref name="DG2_4" /><ref>{{cite web|url=https://www.mindat.org/min-2512.html|title=Mackinawite|publisher=Mindat.org|access-date=3 April 2018|archive-date=3 January 2019|archive-url=https://web.archive.org/web/20190103005122/https://www.mindat.org/min-2512.html|url-status=live}}</ref> Other examples include layered crystals with variable layer stacking, or crystals that differ only in the regular arrangement of [[Vacancy defect|vacancies]] and substitutions. On the other hand, some substances that have a continuous series of compositions, may be arbitrarily split into several minerals. The typical example is the [[olivine]] group (Mg, Fe)<sub>2</sub>SiO<sub>4</sub>, whose magnesium-rich and iron-rich end-members are considered separate minerals ([[forsterite]] and [[fayalite]]).

The details of these rules are somewhat controversial.<ref name="DG2_4" /> For instance, there have been several recent proposals to classify amorphous substances as minerals, but they have not been accepted by the IMA.

The IMA is also reluctant to accept minerals that occur naturally only in the form of [[nanoparticle]]s a few hundred atoms across, but has not defined a minimum crystal size.<ref name=nick1998/>

Some authors require the material to be a [[thermodynamic stability|stable or metastable]] solid at [[room temperature]] (25&nbsp;°C).<ref name="DG2_4">{{Cite book|title = Mineralogy and Optical Mineralogy |author=Melinda Darby Dyar |author2=Mickey E. Gunter |publisher = Mineralogical Society of America|year = 2007|isbn = 978-0-939950-81-2|pages = 2–4}}</ref>  However, the IMA only requires that the substance be stable enough for its structure and composition to be well-determined. For example, it recognizes [[meridianiite]] (a naturally occurring hydrate of [[magnesium sulfate]]) as a mineral, even though it is formed and stable only below 2&nbsp;°C.

{{As of|2025|03}}, 6,126 mineral species are approved by the IMA.<ref name="IMAMineralsCount"/> They are most commonly [[List of minerals named after people|named after a person]], followed by discovery location; names based on chemical composition or physical properties are the two other major groups of mineral name etymologies.<ref name="DG20-22"/><ref>{{harvnb|Dyar|Gunter|2008}}, p. 556</ref>  Most names end in "-ite"; the exceptions are usually names that were well-established before the organization of mineralogy as a discipline, for example [[galena]] and [[diamond]].

===Biogenic minerals===
{{further|Biomineralization}}

A topic of contention among geologists and mineralogists has been the IMA's decision to exclude biogenic crystalline substances. For example, Lowenstam (1981) stated that "organisms are capable of forming a diverse array of minerals, some of which cannot be formed inorganically in the biosphere."<ref name="Lowenstam81">{{cite journal | first1=Lowenstam | last1=H.A. | title=Minerals formed by organisms | journal=Science | date=1981 | volume=211 | issue=4487 | pages=1126–31 | doi=10.1126/science.7008198 | jstor=1685216 | pmid=7008198|bibcode = 1981Sci...211.1126L }}</ref>

Skinner (2005) views all solids as potential minerals and includes [[biomineralization|biominerals]] in the mineral kingdom, which are those that are created by the metabolic activities of organisms. Skinner expanded the previous definition of a mineral to classify "element or compound, amorphous or crystalline, formed through ''[[Biogeochemistry|biogeochemical]] '' processes," as a mineral.<ref name="Skinner05" />

Recent advances in high-resolution [[genetics]] and [[X-ray absorption spectroscopy]] are providing revelations on the biogeochemical relations between [[microorganism]]s and minerals that may shed new light on this question.<ref name=Nickel /><ref name="Skinner05">{{cite journal | last1=Skinner | first1=H.C.W. | title=Biominerals | journal=Mineralogical Magazine | volume=69 | issue=5 | pages=621–41| doi=10.1180/0026461056950275 | date=2005 | bibcode=2005MinM...69..621S | s2cid=232388764 }}</ref> For example, the IMA-commissioned "Working Group on Environmental Mineralogy and Geochemistry " deals with minerals in the [[hydrosphere]], [[atmosphere]], and [[biosphere]].<ref>{{cite web|title=Working Group on Environmental Mineralogy and Geochemistry|url=https://www.ima-mineralogy.org/WGEMG_objectives.htm|website=Commissions, working groups and committees|publisher=International Mineralogical Association|access-date=4 April 2018|language=en|date=3 August 2011|archive-date=8 March 2020|archive-url=https://web.archive.org/web/20200308103719/https://www.ima-mineralogy.org/WGEMG_objectives.htm|url-status=live}}</ref> The group's scope includes mineral-forming microorganisms, which exist on nearly every rock, soil, and particle surface spanning the globe to depths of at least 1600 metres below the [[Seabed|sea floor]] and 70 kilometres into the [[stratosphere]] (possibly entering the [[mesosphere]]).<ref name="Takai10">{{cite book | last=Takai | first=K. | chapter=Limits of life and the biosphere: Lessons from the detection of microorganisms in the deep sea and deep subsurface of the Earth. | title=Origins and Evolution of Life: An Astrobiological Perspective | editor1-last=Gargaud | editor1-first=M. | editor2-last=Lopez-Garcia | editor2-first=P. | editor3-last=Martin | editor3-first=H. | pages=469–86 | date=2010 | publisher=Cambridge University Press | location=Cambridge |isbn= 978-1-139-49459-5}}</ref><ref name="Roussel08">{{cite journal | last1=Roussel | first1=E.G. | last2=Cambon Bonavita | first2=M. | last3=Querellou | first3=J. | last4=Cragg | first4=B.A. | last5=Prieur | first5=D. | last6=Parkes | first6=R.J. | title=Extending the Sub-Sea-Floor Biosphere | journal=Science | date=2008 | volume=320 | issue=5879 | page=1046 | doi=10.1126/science.1154545 | last7=Parkes | first7=R.J. | bibcode=2008Sci...320.1046R | pmid=18497290 | s2cid=23374807 | url=https://archimer.ifremer.fr/doc/00000/4209/ | access-date=2019-02-01 | archive-date=2020-05-10 | archive-url=https://web.archive.org/web/20200510114404/https://archimer.ifremer.fr/doc/00000/4209/ | url-status=live }}</ref><ref name="Pearce09">{{cite journal | last1=Pearce | first1=D.A. | last2=Bridge | first2=P.D. | last3=Hughes | first3=K.A. | last4=Sattler | first4=B. | last5=Psenner | first5=R. | last6=Russel | first6=N.J. | title= Microorganisms in the atmosphere over Antarctica | volume=69 | issue=2 | pages=143–57 | journal=FEMS Microbiology Ecology | doi=10.1111/j.1574-6941.2009.00706.x| date=2009 | pmid=19527292| doi-access=free | bibcode=2009FEMME..69..143P }}</ref>

[[Biogeochemical cycle]]s have contributed to the formation of minerals for billions of years. Microorganisms can [[Precipitation (chemistry)|precipitate]] metals from [[Solution (chemistry)|solution]], contributing to the formation of [[ore]] deposits. They can also [[Catalysis|catalyze]] the [[Dissolution (chemistry)|dissolution]] of minerals.<ref name="Newman02">{{cite journal | last1=Newman | first1=D.K. | last2=Banfield | first2=J.F. | title=Geomicrobiology: How Molecular-Scale Interactions Underpin Biogeochemical Systems | journal=Science | volume=296 | issue=5570 | pages=1071–77 | doi=10.1126/science.1010716 | date=2002 | pmid=12004119| bibcode=2002Sci...296.1071N | s2cid=1235688 }}</ref><ref name="Warren03">{{cite journal | last1=Warren | first1=L.A. | last2=Kauffman | first2=M.E. | title=Microbial geoengineers | journal=Science | date=2003 | volume=299 | issue=5609 | pages=1027–29 | doi=10.1126/science.1072076 | jstor=3833546 | pmid=12586932| s2cid=19993145 }}</ref><ref name="González-Muñoz10">{{cite journal | last1=González-Muñoz | first1=M.T. | last2=Rodriguez-Navarro | first2=C. | last3=Martínez-Ruiz | first3=F. | last4=Arias | first4=J.M. | last5=Merroun | first5=M.L. | last6=Rodriguez-Gallego | first6=M. | title=Bacterial biomineralization: new insights from Myxococcus-induced mineral precipitation | journal=Geological Society, London, Special Publications | volume=336 | issue=1 | pages=31–50 | doi=10.1144/SP336.3 | bibcode=2010GSLSP.336...31G| year=2010 | s2cid=130343033 }}</ref>

Prior to the International Mineralogical Association's listing, over 60 biominerals had been discovered, named, and published.<ref name="Veis90">{{cite journal | last1=Veis | first1=A. | title=Biomineralization. Cell Biology and Mineral Deposition. by Kenneth Simkiss; Karl M. Wilbur On Biomineralization. by Heinz A. Lowenstam; Stephen Weiner | journal=Science | volume=247 | issue=4946 | pages=1129–30 | jstor=2874281 | date=1990 | pmid=17800080 | doi=10.1126/science.247.4946.1129|bibcode = 1990Sci...247.1129S }}</ref> These minerals (a sub-set tabulated in Lowenstam (1981)<ref name="Lowenstam81" />) are considered minerals proper according to Skinner's (2005) definition.<ref name="Skinner05" /> These biominerals are not listed in the International Mineral Association official list of mineral names;<ref>[http://pubsites.uws.edu.au/ima-cnmnc/IMA%20mineral%20list%20update%20BB%20Upload%208%20April%202011.pdf Official IMA list of mineral names (updated from March 2009 list)] {{webarchive|url=https://web.archive.org/web/20110706121228/http://pubsites.uws.edu.au/ima-cnmnc/IMA%20mineral%20list%20update%20BB%20Upload%208%20April%202011.pdf |date=2011-07-06 }}. uws.edu.au</ref>  however, many of these biomineral representatives are distributed amongst the 78 mineral classes listed in the Dana classification scheme.<ref name="Skinner05" />

Skinner's (2005) definition of a mineral takes this matter into account by stating that a mineral can be crystalline or amorphous.<ref name="Skinner05" /> Although biominerals are not the most common form of minerals,<ref name=Hefferan10>{{cite book | first1=Hefferan | last1=K. | first2=O'Brien | last2=J. | title=Earth Materials | date=2010 | isbn=978-1-4443-3460-9 | publisher=Wiley-Blackwell}}</ref> they help to define the limits of what constitutes a mineral proper. Nickel's (1995) formal definition explicitly mentioned crystallinity as a key to defining a substance as a mineral. A 2011 article defined [[icosahedrite]], an aluminium-iron-copper alloy, as a mineral; named for its unique natural [[icosahedral symmetry]], it is a [[quasicrystal]]. Unlike a true crystal, quasicrystals are ordered but not periodic.<ref>{{cite journal | last = Bindi | first = L. | author-link = Luca Bindi | author2 = Paul J. Steinhardt | author3 = Nan Yao | author4 = Peter J. Lu | title = Icosahedrite, Al<sub>63</sub>Cu<sub>24</sub>Fe<sub>13</sub>, the first natural quasicrystal | journal = American Mineralogist | volume = 96 | issue = 5–6 | pages = 928–31 | date = 2011| doi = 10.2138/am.2011.3758 | bibcode = 2011AmMin..96..928B | s2cid = 101152220 }}</ref><ref>Commission on New Minerals and Mineral Names, [http://pubsites.uws.edu.au/ima-cnmnc/newminerals2010.pdf Approved as new mineral] {{webarchive|url=https://web.archive.org/web/20120320182918/http://pubsites.uws.edu.au/ima-cnmnc/newminerals2010.pdf |date=2012-03-20 }}</ref>