{{Short description|Phyllosilicate mineral}} {{Infobox mineral | name = Kampfite | image = Traskite (brown)-Kampfite (bluish).jpg | imagesize = 260px | alt = | caption = Traskite (brown) and Kampfite (bluish), from Big Creek, Fresno County, California, United States of America | category = Phyllosilicate minerals | formula = {{chem2|Ba12(Si11Al5)O31(CO3)8Cl5}} | IMAsymbol = Kpfb<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> | strunz = 9.EG.20 | dana = | system = Monoclinic | class = Domatic (m) <br/><small>(same H-M symbol)</small> | symmetry = ''Cc'' | unit cell = a = 31.2329, b = 5.2398 <br/>c = 9.0966&nbsp;[Å]; β = 106.933°; Z&nbsp;=&nbsp;1 | color = Light blue gray | habit = Irregular grains or anhedral crystal inclusions | twinning = | cleavage = Good on {001} | fracture = Uneven | tenacity = Brittle | mohs = 3 | luster = Vitreous | streak = White | diaphaneity = Translucent | gravity = 3.45 | density = | polish = | opticalprop = Uniaxial – (strongly pseudohexagonal) | refractive = n<sub>ω</sub> = 1.642 n<sub>ε</sub> = 1.594 | birefringence = δ = 0.048 | pleochroism = | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | prop1 = | prop1text = | references = <ref name=mindat>[http://www.mindat.org/min-10386.html Kampfite on Mindat.org]</ref><ref name=Webmin>[https://www.webmineral.com/data/Kampfite.shtml#.UpvfktLjW1U Kampfite data on Webmin]</ref> }} '''Kampfite''' is a rare barium silicate–carbonate–halide mineral with the chemical formula {{chem2|Ba12(Si11Al5)O31(CO3)8Cl5}}. Discovered in 1964 and described in 2001, it is named after Anthony R. Kampf. The mineral is known only from Fresno County, California.

==Description== Kampfite is translucent and light blue-gray in color. Specimens occur as irregular masses up to {{convert|1|cm|in|abbr=on}} in size.<ref name=handbook>{{cite encyclopedia|url=https://www.handbookofmineralogy.org/pdfs/kampfite.pdf |title=Kampfite |encyclopedia=Handbook of Mineralogy |editor1-first=John W. |editor1-last=Anthony|editor2-first=Richard A. |editor2-last=Bideaux|editor3-first=Kenneth W. |editor3-last=Bladh|editor4-first= Monte C. |editor4-last=Nichols |publisher=Mineralogical Society of America|location=Chantilly, VA}}</ref>

==Composition and structure== When first described, the formula was identified as {{chem2|Ba6[(Si,Al)O2]8(CO3)2Cl2(Cl,H2O)2}}.{{sfn|Basciano|Groat|Roberts|Grice|2001|p=1053}} Subsequent work on analyzing the crystal structure led to a revised formula of {{chem2|Ba12(Si11Al5)O31(CO3)8Cl5}}. The structural {{chem2|H2O}} noted in the original description was not found in the later work.{{sfn|Basciano|Groat|2007|p=942}}

The structure consists of double layers of tetrahedra connected by barium-containing polyhedra. It is this layering which causes kampfite's one perfect cleavage.{{sfn|Basciano|Groat|2007|p=935}}{{sfn|Basciano|Groat|2007|p=940}} Kampfite shares chemical and structural similarities with cymrite.{{sfn|Basciano|Groat|2007|p=935}} {{As of|2007}}, it is the only known barium silicate carbonate aside from fencooperite.{{sfn|Basciano|Groat|2007|p=942}}

==Occurrence== Kampfite has been found in association with celsian, fresnoite, macdonaldite, pyrrhotite, titantaramellite, traskite, and witherite.<ref name=handbook/> The mineral is known only from locations in Fresno County, California.<ref name=mindat/><ref name=handbook/> Kampfite is found in quartz-rich regions of sanbornite rocks{{sfn|Basciano|Groat|Roberts|Grice|2001|p=1053}} within gneiss which has undergone contact metamorphism associated with an adjacent granodiorite intrusive.<ref name=handbook/>

==History== The mineral discovered in 1964 by Robert Walstrom from the Esquire #1 claim of the Rush Creek deposit in eastern Fresno County.{{sfn|Basciano|Groat|Roberts|Grice|2001|p=1054}} It was described in 2001 in ''The Canadian Mineralogist''.{{sfn|Basciano|Groat|Roberts|Grice|2001|p=1053}} The mineral was named ''kampfite'' in honor of Anthony Robert Kampf (1948–), curator of the Los Angeles County Museum of Natural History, for his crystallography work on new and rare minerals.{{sfn|Basciano|Groat|Roberts|Grice|2001|p=1054}}

Co-type specimens are held by the University of British Columbia and the Geological Survey of Canada.{{sfn|Basciano|Groat|Roberts|Grice|2001|pp=1054–1055}}

==References== {{reflist|30em}}

===Bibliography=== *{{cite journal|display-authors=4|last1=Basciano|first1=Laurel C.|last2=Groat|first2=Lee A.|last3=Roberts|first3=Andrew C.|last4=Grice|first4=Joel D.|last5=Dunning|first5=Gail E.|last6=Foord|first6=Eugene E.|last7=Kjarsgaard|first7=Ingrid M.|last8=Walstrom|first8=Robert E.|title=Kampfite, a new barium silicate carbonate mineral species from Fresno County, California|journal=The Canadian Mineralogist|year=2001|volume=39|issue=4|pages=1053–1058|doi=10.2113/gscanmin.39.4.1053|bibcode=2001CaMin..39.1053B |url=https://rruff.info/doclib/cm/vol39/CM39_1053.pdf|citeseerx=10.1.1.553.8742}} *{{cite journal|last1=Basciano|first1=Laurel C.|last2=Groat|first2=Lee A.|title=The crystal structure of kampfite|journal=The Canadian Mineralogist|year=2007|volume=45|issue=4|pages=935–943|doi=10.2113/gscanmin.45.4.935|bibcode=2007CaMin..45..935B |url=https://rruff.info/doclib/cm/vol45/CM45_935.pdf}}

==External links== *[http://www.mindat.org/gallery.php?min=10386 Photos of kampfite] from mindat.org

Category:Barium minerals Category:Carbonate minerals Category:Phyllosilicates Category:Monoclinic minerals Category:Minerals in space group 9