Posnjakite

Posnjakite is a hydrated copper sulfate mineral. It was discovered in the Tungsten deposit of Nura-Taldy^[3] in Karaganda Region in Kazakhstan and described in 1967 by Aleksandr Ivanovich Komkov (1926–1987) and Yevgenii Ivanovich Nefedov (1910–1976)^[4] and named after geochemist Eugene Valdemar Posnjak (1888–1949).^[5]

Posnjakite
Posnjakite from Špania Dolina in Slovakia
General
Category	Copper minerals
Formula (repeating unit)	Cu4[(OH)6|SO4] • H2O
Strunz classification	7.DD.10
Dana classification	31.4.1.1
Crystal system	Monoclinic
Crystal class	Domatic (m) (same H-M symbol)
Space group	Pa
Unit cell	a = 10.578 Å, b = 6.345 Å, c = 7.863 Å; β = 117.98°; Z = 2[1]
Identification
Formula mass	488.32 g/mol
Color	Sky-blue to dark-blue
Crystal habit	Crystals scaly, or as crusts; earthy
Mohs scale hardness	2 to 3
Luster	Vitreous
Refractive index	nα = 1.625 nβ = 1.680 nγ = 1.706 [1]
References	[2]

OccurrenceEdit

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. 

This article uses material from the Wikipedia article  Metasyntactic variable, which is released under the  Creative Commons Attribution-ShareAlike 3.0 Unported License.