Bayldonite

{{Short description|Secondary mineral}} {{Infobox mineral |boxbgcolor=#548469| name = Bayldonite | boxtextcolor = #fff | image = File:Bayldonite-Malachite-160206.jpg | alt = | caption = Bayldonite, Tsumeb, Namibia | category = Arsenate minerals | formula = PbCu₃(AsO₄)₂(OH)₂ |IMAsymbol=Bay<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 = 8.BH.45 | dana = | system = Monoclinic | class = Prismatic (2/m) <br/><small>(same H-M symbol)</small> | symmetry = ''C2/c'' | unit cell = | color = Green, apple-green | colour = | habit = Mammillary crust | twinning =Pseudoscalenohedral trillings with the composition plane | cleavage =None observed | fracture =Irregular/uneven, conchoidal, sub-conchoidal, fibrous | tenacity =Brittle | mohs = {{frac|4|1|2}} | luster = Resinous, waxy, greasy | streak =Siskin green to apple green | diaphaneity =Transparent, translucent | gravity = | density = 5.24–5.65 g/cm³ (measured), 5.707 g/cm³ (calculated) | polish = | opticalprop = Biaxial (+) | refractive = n_α = 1.951 n_β = 1.970 n_γ = 1.991 | birefringence = 0.040 | pleochroism = Non-pleochroic | 2V = 89° | dispersion = r < v strong | extinction = Y^elongation = 45°; X=b | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | prop1 = | prop1text = | references = <ref>[https://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Bayldonite Mineralienatlas]</ref><ref>{{cite web |url=http://webmineral.com/data/Bayldonite.shtml |title=Bayldonite Mineral Data |author= |date= |publisher=Webmineral |accessdate=6 June 2011| archiveurl= https://web.archive.org/web/20110607064909/http://www.webmineral.com/data/Bayldonite.shtml| archivedate= 7 June 2011 <!--DASHBot-->| url-status= live}}</ref><ref>{{cite web |url=http://www.mindat.org/min-581.html |title=Bayldonite mineral information and data |author= |date= |publisher=Mindat |accessdate=6 June 2011}}</ref> }} '''Bayldonite''' (BAIL-done-ite)<ref name="Thomas159" /> is a rare secondary mineral with the chemical formula PbCu₃(AsO₄)₂(OH)₂. Its provenance has been attributed to Penberthy Croft Mine, Cornwall, England, United Kingdom but there is no substantiating evidence for this and it was only attributed to Cornwall by Church (1865). Also, Church’s paper (Church, 1865) clearly states “''I am indebted to Mr. Talling for this mineral species also.''” so the original material was supplied by the mineral dealer Richard Talling and not discovered by Bayldon. <ref>A. H. Church: ''XLI.—Chemical researches on some new and rare cornish minerals''. In: ''Journal of the Chemical Society'', 1865, 18, S. 259-268, {{doi|10.1039/JS8651800259}}.</ref><ref name="Thomas159">{{cite book |title=Gemstones: properties, identification and use |last=Thomas |first=Arthur |year=2008 |publisher=New Holland Publishers |isbn=978-1-84537-602-4 |page=159 |url=https://books.google.com/books?id=MPZK8ILOSR0C&pg=PA159 }}{{Dead link|date=September 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> Bayldonite was named after Church's dear friend and colleague at the Royal Agricultural College (RAC),Cirencester, Gloucestershire John Bayldon MD (1837 – 1872).<ref>A. H. Church: ''XLI.—Chemical researches on some new and rare cornish minerals''. In: ''Journal of the Chemical Society'', 1865, 18, S. 259-268, {{doi|10.1039/JS8651800259}}.</ref> Specimens are also found in Tsumeb, Namibia, and Arizona, United States. It is sometimes used as a gemstone.<ref>Gemstones: Properties, Identification and Use By Arthur Thomas, p.159</ref>

==References== {{Portal|Cornwall}} {{Commons category|Bayldonite}} {{Reflist}}

Category:Arsenate minerals Category:Copper minerals Category:Gemstones Category:Monoclinic minerals Category:Minerals in space group 15

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