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]

Posnjakite
Posnjakite from Špania Dolina in Slovakia
General
CategoryCopper minerals
Formula
(repeating unit)
Cu4[(OH)6|SO4] • H2O
IMA symbolPnk[1]
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[2]
Identification
Formula mass488.32 g/mol
ColorSky-blue to dark-blue
Crystal habitCrystals scaly, or as crusts; earthy
Mohs scale hardness2 to 3
LusterVitreous
Refractive indexnα = 1.625 nβ = 1.680 nγ = 1.706 [2]
References[3]

Occurrence

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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

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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. ^ a b Mindat - Posnjakite
  3. ^ Mineralienatlas
  4. ^ a b Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C. (eds.). "Posnjakite". Handbook of Mineralogy (PDF). Chantilly, VA, USA: Mineralogical Society of America. Retrieved 13 March 2022.
  5. ^ "ПО3НЛRИТ - НОВЫЙ МИНЕРАЛl" [PO3NLRIT - New Mineral] (PDF) (in Russian).
  6. ^ MINER Database, (c) Jacques Lapaire - Minéraux et étymologie Archived 2014-10-06 at the Wayback Machine