Chemistry:Bayldonite

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Short description: Secondary mineral
Bayldonite
Bayldonite-Malachite-160206.jpg
Bayldonite, Tsumeb, Namibia
General
CategoryArsenate minerals
Formula
(repeating unit)
PbCu3(AsO4)2(OH)2
Strunz classification8.BH.45
Crystal systemMonoclinic
Crystal classPrismatic (2/m)
(same H-M symbol)
Space groupC2/c
Identification
ColorGreen, apple-green
Crystal habitMammillary crust
TwinningPseudoscalenohedral trillings with the composition plane
CleavageNone observed
FractureIrregular/uneven, conchoidal, sub-conchoidal, fibrous
TenacityBrittle
Mohs scale hardness4 12
|re|er}}Resinous, waxy, greasy
StreakSiskin green to apple green
DiaphaneityTransparent, translucent
Density5.24–5.65 g/cm3 (measured), 5.707 g/cm3 (calculated)
Optical propertiesBiaxial (+)
Refractive indexnα = 1.951 nβ = 1.970 nγ = 1.991
Birefringence0.040
PleochroismNon-pleochroic
2V angle89°
Dispersionr < v strong
ExtinctionY^elongation = 45°; X=b
References[1][2][3]

Bayldonite (BAIL-done-ite)[5] is a rare secondary mineral with the chemical formula PbCu3(AsO4)2(OH)2. It was first discovered in Penberthy Croft Mine, Cornwall, England, United Kingdom.[5] It is named after its discoverer, John Bayldon (1837(8) – 1872).[6] Specimens are also found in Tsumeb, Namibia, and Arizona, United States . It is sometimes used as a gemstone.[7]

References

  1. Mineralienatlas
  2. "Bayldonite Mineral Data". Webmineral. Archived from the original on 7 June 2011. https://web.archive.org/web/20110607064909/http://www.webmineral.com/data/Bayldonite.shtml. Retrieved 6 June 2011. 
  3. "Bayldonite mineral information and data". Mindat. http://www.mindat.org/min-581.html. Retrieved 6 June 2011. 
  4. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine 85 (3): 291–320. doi:10.1180/mgm.2021.43. Bibcode2021MinM...85..291W. 
  5. 5.0 5.1 Thomas, Arthur (2008). Gemstones: properties, identification and use. New Holland Publishers. p. 159. ISBN 978-1-84537-602-4. https://books.google.com/books?id=MPZK8ILOSR0C&pg=PA159. [yes|permanent dead link|dead link}}]
  6. 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.
  7. Gemstones: Properties, Identification and Use By Arthur Thomas, p.159