Mineralogy and Petrology

, Volume 103, Issue 1–4, pp 169–175 | Cite as

Agricolaite, a new mineral of uranium from Jáchymov, Czech Republic

  • Roman Skála
  • Petr Ondruš
  • František Veselovský
  • Ivana Císařová
  • Jan Hloušek
Original Paper

Abstract

The new mineral agricolaite, a potassium uranyl carbonate with ideal formula K4(UO2)(CO3)3, occurs in vugs of ankerite gangue in gneisses in the abandoned Giftkiesstollen adit at Jáchymov, Czech Republic. The name is after Georgius Agricola (1494–1555), German scholar and scientist. Agricolaite occurs as isolated equant irregular translucent grains to 0.3 mm with yellow color, pale yellow streak, and vitreous luster. It is brittle with uneven fracture and displays neither cleavage nor parting. Agricolaite is non-fluorescent. Mohs hardness is ~4. It is associated with aragonite, brochantite, posnjakite, malachite, rutherfordine, and “pseudo-voglite”. Experimental density is higher than 3.3 g.cm−3, Dcalc is 3.531 g. cm−3. The mineral is monoclinic, space group C2/c, with a 10.2380(2), b 9.1930(2), c 12.2110(3) Å, β 95.108(2)°, V 1144.71(4) Å3, Z = 4. The strongest lines in the powder X-ray diffraction pattern are d(I)(hkl): 6.061(55)(002), 5.087(57)(200), 3.740(100)(202), 3.393(43)(113), 2.281(52)(402). Average composition based on ten electron microprobe analyses corresponds to (in wt.%) UO3 48.53, K2O 31.49, CO2(calc) 22.04 which gives the empirical formula K3.98(UO2)1.01(CO3)3.00. The crystal structure was solved from single-crystal X-ray diffraction data and refined to R 1 = 0.0184 on the basis of the 1,308 unique reflections with F o > 4σF o. The structure of agricolaite is identical to that of synthetic K4(UO2)(CO3)3 and consists of separate UO2(CO3)3 groups organized into layers parallel to (100) and two crystallographically non-equivalent sites occupied by K+ cations. Both the mineral and its name were approved by the IMA-CNMNC.

Keywords

Aragonite Malachite Ankerite German Scholar Brochantite 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Notes

Acknowledgements

We wish to thank Radek Škoda who performed chemical microprobe analyses of the mineral. The funding of the research was through the institutional research plan AV0Z30130516. Reviews by U. Kolitsch and an anonymous reviewer helped to improve the manuscript. Editorial handling by A. Beran is acknowledged.

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Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Roman Skála
    • 1
  • Petr Ondruš
    • 2
  • František Veselovský
    • 3
  • Ivana Císařová
    • 4
  • Jan Hloušek
    • 5
  1. 1.Institute of Geology ASCR, v.v.i.Praha 6Czech Republic
  2. 2.Praha 1Czech Republic
  3. 3.Czech Geological SurveyPraha 1Czech Republic
  4. 4.Department of Inorganic ChemistryCharles UniversityPraha 2Czech Republic
  5. 5.JáchymovCzech Republic

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