Journal of

GEOsciences

  (Formerly Journal of the Czech Geological Society)

Letter to editor

Jakub Plášil

Crystal structure refinement of pseudojohannite, Cu₃(OH)₂[(UO₂)₄O₄(SO₄)₂](H₂O)₁₂, from the type locality - Jáchymov, Czech Republic

Journal of Geosciences, volume 60 (2015), issue 2, 123 - 127

DOI: http://doi.org/10.3190/jgeosci.190

The crystal structure of pseudojohannite from the type locality, Jáchymov (Western Bohemia, Czech Republic), was solved by charge-flipping method from single-crystal X ray diffraction data and refined to an R = 0.0385 against 2072 unique observed reflections. Pseudojohannite from Jáchymov is triclinic, P 1, with a = 8.6653(4), b = 8.8499(5) Å, c = 9.9908(6), α = 72.103(6), β = 70.512(5)°, γ = 76.070(5)°, V = 679.12(7) ų and Z = 1. The structural formula derived from the refinement and bond-valence considerations is Cu₃(OH)₂[(UO₂)₄O₄(SO₄)₂](H₂O)₁₂, confirming previous structure determination on the material from Widowmaker mine, Utah, USA. Contrary to other members of the zippeite-group, the interstitial metal sites in pseudojohannite (populated by Cu²⁺), are fully occupied and the structure tends to be fully ordered with no important departure from the ideal stoichiometry.