Chemistry:Ungemachite

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Ungemachite
General
CategorySulfate mineral
Formula
(repeating unit)
K3Na8Fe(SO4)6(NO3)2•6H2O
Strunz classification7.DG.10
Dana classification32.2.3.1
Crystal systemTrigonal
Crystal classR3
Unit cella = 10.898 Å, c = 24.989 Å
Identification
Colourpale yellow
Fractureuneven
Tenacitybrittle
Mohs scale hardness2⁠1/2⁠
|re|er}}vitreous
Density2.287
Optical propertiesuniaxial (−)
Refractive indexnω = 1.502 nε = 1.449
Birefringence0.053
References[1]

Ungemachite is a rare mineral (K3Na8Fe(SO4)6(NO3)2 · 6H2O) known from only two locations - a copper deposit in the Atacama Desert (Chile) and in the New Cobar copper–gold deposit, New South Wales (Australia). The formation of Ungemachite requires the presence of nitrate minerals, which requires arid conditions, as well as sulfates. It has been synthesized under laboratory conditions and its properties have been studied.[2] The mineral was described in 1936 and is named after the mineralogist Henri Ungemach.[3][4][5]

References

  1. ↑ "Ungemachite". https://www.mindat.org/min-4095.html. 
  2. ↑ Vargas Jentzsch, Paul; Ciobotă, Valerian; Bolanz, Ralph Michael; Kampe, Bernd; Rösch, Petra; Majzlan, Juraj; Popp, Jürgen (2012). "Raman and infrared spectroscopic study of synthetic ungemachite, K3Na8Fe(SO4)6(NO3)2·6H2O" (in en). Journal of Molecular Structure 1022: 147–152. doi:10.1016/j.molstruc.2012.05.024. https://linkinghub.elsevier.com/retrieve/pii/S0022286012004565. 
  3. ↑ Warr, Laurence N. (2021). "IMA–CNMNC approved mineral symbols" (in en). Mineralogical Magazine 85 (3): 291–320. doi:10.1180/mgm.2021.43. ISSN 0026-461X. Bibcode: 2021MinM...85..291W. https://www.cambridge.org/core/product/identifier/S0026461X21000438/type/journal_article. 
  4. ↑ Groat, Lee A.; Hawthorne, F. C. (1986). "Structure of ungemachite, K3Na8Fe3+) (SO4)6(NO3)2.6H2O, a mixed sulfate-nitrate mineral". American Mineralogist 71 (5–6): 826–829. 
  5. ↑ Peacock, M. A.; Bandy, M. C. (1936). "Ungemachite and clino-ungemachite: new minerals from Chile.". American Mineralogist 21 (12): 2. http://www.minsocam.org/ammin/AM21/AmMin_v21_n12_Pt_2.pdf.