Bayldonite

Bayldonite
Bayldonite
	Bayldonite, Tsumeb, Namibia
General
Category	Arsenate minerals
Formula; (repeating unit)	PbCu3(AsO4)2(OH)2
IMA symbol	Bay
Strunz classification	8.BH.45
Crystal system	Monoclinic
Crystal class	Prismatic (2/m) ; (same H-M symbol)
Space group	C2/c
Identification
Color	Green, apple-green
Crystal habit	Mammillary crust
Twinning	Pseudoscalenohedral trillings with the composition plane
Cleavage	None Observed
Fracture	Irregular/Uneven, Conchoidal, Sub-Conchoidal, Fibrous
Tenacity	Brittle
Mohs scale hardness	4+1⁄2
Luster	Resinous, Waxy, Greasy
Streak	Siskin green to apple green
Diaphaneity	Transparent, Translucent
Density	5.24–5.65 g/cm3 (measured), 5.707 g/cm3 (calculated)
Optical properties	Biaxial (+)
Refractive index	nα = 1.951 nβ = 1.970 nγ = 1.991
Birefringence	0.040
Pleochroism	Non-pleochroic
2V angle	89°
Dispersion	r < v strong
Extinction	Y^elongation = 45°; X=b
References

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[]

^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
^ Mineralienatlas
^ "Bayldonite Mineral Data". Webmineral. Archived from the original on 7 June 2011. Retrieved 6 June 2011.
^ "Bayldonite mineral information and data". Mindat. Retrieved 6 June 2011.
^ ^a ^b Thomas, Arthur (2008). Gemstones: properties, identification and use. New Holland Publishers. p. 159. ISBN 978-1-84537-602-4.
^ 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.
^ Gemstones: Properties, Identification and Use By Arthur Thomas, p.159

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[1] Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.

[2] Mineralienatlas

[3] "Bayldonite Mineral Data". Webmineral. Archived from the original on 7 June 2011. Retrieved 6 June 2011.

[4] "Bayldonite mineral information and data". Mindat. Retrieved 6 June 2011.

[Thomas159-5] Thomas, Arthur (2008). Gemstones: properties, identification and use. New Holland Publishers. p. 159. ISBN 978-1-84537-602-4.

[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

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