Chemistry:Posnjakite

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Posnjakite
Posnjakite-113800.jpg
Posnjakite from Špania Dolina in Slovakia
General
CategoryCopper minerals
Formula
(repeating unit)
Cu4[(OH)6|SO4] • H2O
Strunz classification7.DD.10
Dana classification31.4.1.1
Crystal systemMonoclinic
Crystal classDomatic (m)
(same H-M symbol)
Space groupPa
Unit cella = 10.578 Å,
b = 6.345 Å,
c = 7.863 Å;
β = 117.98°; Z = 2[1]
Identification
Formula mass488.32 g/mol
ColorSky-blue to dark-blue
Crystal habitCrystals scaly, or as crusts; earthy
Mohs scale hardness2 to 3
|re|er}}Vitreous
Refractive indexnα = 1.625 nβ = 1.680 nγ = 1.706 [1]
References[2]

Posnjakite is a hydrated copper sulfate mineral. It was discovered in the Tungsten deposit of Nura-Taldy[4] in Karaganda Region in Kazakhstan and described in 1967 by Aleksandr Ivanovich Komkov (1926–1987) and Yevgenii Ivanovich Nefedov (1910–1976)[5] and named after geochemist Eugene Valdemar Posnjak (1888–1949).[6]

Occurrence

Posnjakite is an uncommon but widespread secondary mineral in the oxidised zone of copper sulfide deposits, which may be of post-mine formation. It is associated with brochantite, langite, devilline, serpierite, woodwardite, wroewolfeite, aurichalcite, azurite, malachite and chalcopyrite.[4]

References

  1. 1.0 1.1 Mindat - Posnjakite
  2. Mineralienatlas
  3. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine 85 (3): 291–320. doi:10.1180/mgm.2021.43. Bibcode2021MinM...85..291W. 
  4. 4.0 4.1 "Posnjakite". Handbook of Mineralogy. Chantilly, VA, USA: Mineralogical Society of America. http://rruff.geo.arizona.edu/doclib/hom/posnjakite.pdf. Retrieved 13 March 2022. 
  5. http://rruff.info/uploads/ZVMO96N1_58.pdf [bare URL PDF]
  6. MINER Database, (c) Jacques Lapaire - Minéraux et étymologie