Challacolloite

{{Short description|Chloride mineral}} {{Infobox mineral | name = Challacolloite | boxwidth = | boxbgcolor = | image = Challacolloite.jpg | imagesize = | alt = | caption = Honey yellow Challacolloite crystals from the famous locality of La Fossa Crater (Vulcano Island, Aeolian Islands, Sicily, Italy) | struct image = | struct caption = | struct imagesize = | struct2 image = | struct2 caption = | struct2 imagesize = | SMILES = | Jmol = | category = | formula = {{chem2|KPb2Cl5}} | IMAsymbol = Chc<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 = 630.83 gm | strunz = 3.AA.55 (10th) | dana = 11.4.2.1 | system = Monoclinic | class = 2/m - Prismatic | symmetry = | unit cell = 878.2 Å³ | colour = Colourless to white | habit = Aggregate | twinning = | cleavage = | fracture = Brittle, subconchoidal fragments | tenacity = | toughness = | mohs = 2-3 | luster = Adamantine/Greasy | streak = White | diaphaneity = | gravity = 4.77 (Calculated) | density = 4.77 g/cm3 (Calculated) | polish = | opticalprop = Biaxial (+), a=2.004, b=2.01, g=2.024, bire=0.0200 | refractive = nα = 2.004 nβ = 2.010 nγ = 2.024 | birefringence = | pleochroism = | 2V = 67° (calculated) | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | Curie temp = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | prop1 = | prop1text = | references = }} '''Challacolloite''', KPb2Cl5, is a rare halide mineral. It crystallizes in the monoclinic system (with space group ''P21/c''<ref>{{cite journal |last1=Mitolo |first1=D. |last2=Pinto |first2=D. |last3=Garavelli |first3=A. |last4=Bindi |first4=L. |last5=Vurro |first5=F. |title=The role of the minor substitutions in the crystal structure of natural challacolloite, KPb2Cl5, and hephaistosite, TlPb2Cl5, from Vulcano (Aeolian Archipelago, Italy) |journal=Mineralogy and Petrology |date=May 2009 |volume=96 |issue=1–2 |pages=121–128 |doi=10.1007/s00710-008-0041-2|bibcode=2009MinPe..96..121M |s2cid=128797167 }}</ref>) and occurs as white fumarolic encrustations on lava. It occurs as intergrowths with cotunnite.<ref name=Webmin>[http://webmineral.com/data/Challacolloite.shtml Webmineral]</ref>

It was first described from a finding at the Challacollo Mine, Iquique, Chile and thereafter identified in specimens from the 1855 Mount Vesuvius eruption and from the Kudryavyi volcano in the Kuriles and also from the Satsuma-Iwojima volcano in Japan.<ref name=Mindat>[http://www.mindat.org/min-27422.html Mindat with location data]</ref> It was recognized as a valid mineral species by the IMA (International Mineralogical Association) in 2005.<ref name=Mindat/>

Artificially grown KPb2Cl5 crystals are used for lasers.<ref>Jochen Schlüter, Dieter Pohl and Sergey Britvin; ''The new mineral challacolloite, KPb2Cl5, the natural occurrence of a technically known laser material,'' N. Jb. Miner. Abh., 2005, Vol.182/1, p. 95–101 [http://www.schweizerbart.de/resources/downloads/paper_previews/57464.pdf pdf]</ref>

== External links == {{Reflist}}

Category:Potassium minerals Category:Lead minerals Category:Chloride minerals Category:Monoclinic minerals Category:Minerals in space group 14 Category:Minerals described in 1855