Agardit-(Ce) ze supergenní zóny ložiska Vrančice u Příbrami (Česká republika)

Pages 217-220
Bulletin mineralogicko-petrologického oddělení Národního muzea v Praze | 2008/16/2

Agardite-(Ce) from supergene zone of the Vrančice ore deposit near Příbram, Czech Republic Samples containing agardite-(Ce) were found in remnants of mine dumps of abandoned ore deposit Vrančice near Příbram, central Bohemia, Czech Republic. Agardite-(Ce) forms radial light green aggregates up to 1 mm in size associated with chrysocolla. Its individual acicular light greenish crystals up to 50 - 200 μm in length are transparent with vitreous luster. Agardite-(Ce) is hexagonal, space group P63/m, the unit-cell parameters refined from X-ray powder data are: a = 13.564(3), c = 5.895(2) Å, V = 939.3(4) Å3. Chemical analyses yielded the average composition CuO 45.24, CaO 2.24, FeO 0.98, PbO 0.21, Y2O3 1.72, Nd2O3 1.31, Sm2O3 0.47, La2O3 1.13, Ce2O3 2.65, SiO2 1.65, As2O5 26.49, P2O5 2.02, H2O (10.59), F 0.20, O=F -0.08, total (96.83) wt. %, corresponding to empirical formula (Ca0.42Ce0.17Y0.16 Fe0.14Nd0.08La0.07Sm0.02Pb0.01)Σ1.07Cu5.96[(AsO4)1.84(AsO3OH)0.57(PO4)0.30(SiO4)0.29]Σ3.00 [(OH)5.73F0.11]Σ5.84 . 3H2O on the basis of (As+P+Si) = 3 apfu.

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