Editing Pyrochlore (section)

{{short description|Niobium mineral of A2B2O7 general formula}}
{{Infobox mineral
| name        = Pyrochlore
| category    = [[Oxide mineral]]
| boxwidth    = 
| boxbgcolor  = 
| image       = Pyrochlore-180063.jpg
| caption     = Pyrochlore from Russia
| formula     = {{chem2|(Na,Ca)2Nb2O6(OH,F)}}
| IMAsymbol   = Pcl<ref>{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616|doi-access=free}}</ref>
| molweight   = 
| strunz      = 4.DH.15
| dana        = 08.02.01.01 <br/>Pyrochlore group
| system      = [[Cubic (crystal system)|Isometric]] 
| class       = Hexoctahedral (m{{overline|3}}m) <br/>[[H-M symbol]]: (4/m {{overline|3}} 2/m)
| symmetry    = ''F''d{{overline|3}}m (No. 227)
| unit cell   = ''a''&nbsp;=&nbsp;10.41(6)&nbsp;Å, ''Z''&nbsp;=&nbsp;8
| color       = Black to brown, chocolate-brown, reddish brown, amber-orange, red-orange
| habit       = Typically octahedra, disseminated granular, massive
| twinning    = 111 rare
| cleavage    = 111 indistinct, may be a parting.
| fracture    = Subconchoidal to uneven, splintery
| tenacity    = Brittle
| mohs        = 5.0–5.5
| luster      = Vitreous to resinous
| polish      = 
| refractive  = ''n''&nbsp;=&nbsp;1.9–2.2
| opticalprop = Isotropic, weak anomalous anisotropism
| birefringence = 
| pleochroism = 
| streak      = White
| gravity     = 4.45 to 4.90
| melt        = 
| fusibility  = 
| diagnostic  = 
| solubility  = 
| diaphaneity = Subtranslucent to opaque
| other       = [[Image:Radioactive.svg|25px]] [[Radioactive]], often [[metamict]]
| references  = <ref>{{Cite web|url=https://www.mineralienatlas.de/lexikon/index.php/MineralData?lang=de&mineral=Pyrochlor|title=Pyrochlor|website=www.mineralienatlas.de}}</ref><ref name="Handbook">{{Cite web |title = pyrochlore at RRuff database |work = rruff.info |access-date = 2015-02-03 |url = http://rruff.info/doclib/hom/pyrochlore.pdf}}</ref><ref name="Mindat">{{Cite web |title = Pyrochlore Group: Pyrochlore Group mineral information and data. |work = mindat.org |access-date = 2015-02-03 |url = http://www.mindat.org/min-3316.html}}</ref><ref name="webmin">{{Cite web |title = Pyrochlore Mineral Data |last = Barthelmy |first = Dave |work = webmineral.com |access-date = 2015-02-03 |url = http://webmineral.com/data/Pyrochlore.shtml#.VNGZoUejO-0}}</ref>
}}
'''Pyrochlore''' ({{chem2|[[sodium|Na]],[[calcium|Ca]])2[[niobium|Nb]]2[[oxygen|O]]6([[hydroxide|OH]],[[fluorine|F]]}}) is a mineral group of the [[niobium]] end member of the pyrochlore supergroup. Pyrochlore is also a term for the crystal structure [[Cubic crystal system#Crystal classes|''F''d{{overline|3}}m]]. The name is from the [[Ancient Greek language|Greek]] {{lang|grc|πῦρ}}, ''fire'', and {{lang|grc|χλωρός}}, ''green'' because it typically turns green on ignition in classic blowpipe analysis.<ref name="Mindat" />