Chanabayaite, Cu₂(N₃C₂H₂)₂Cl(NH₃Cl,H₂О,□)₄ a new mineral containing triazolate anion

Chukanov N. V., Zubkova N. V., Möhn G., Pekov I. V., Pushcharovsky D. Yu., Zadov A. E.

Zapiski RMO (Proceedings of the Russian Mineralogical Society). 2015. V. 144. N 2. P. 36-47

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Language: Russian

Abstract

The new mineral chanabayaite was discovered in a guano deposit located on the Pabellon de Pica Mountain, near Chanabaya village, Iquique Province, Tarapaca region, Chile. Associated minerals are salammoniac, halite, joanneumite, nitratine and earlier chalcopyrite. Chanabayaite forms blue translucent imperfect prismatic crystals up to 0.050.10.5 mm in size and their radial aggregates. Chanabayaite is brittle, with the Mohs’ hardness 2, perfect cleavage on (001) and imperfect cleavage on (100) and (010). D_meas = 1.48(2) g/cm³, D_calc = 1.464 g/cm³. The mineral is optically biaxial (–), α = 1.561(2), β = 1.615(3), γ = 1.620(2), 2V_meas = 25(10)°, 2V_calc = 33°. Pleochroism is strong, Z  Y (deep blue) >> X (pale grey-blue). IR spectrum is given. Chemical composition (electron microprobe for Cu, Fe and Cl; gas chromatography for H, N, C and O) is as follows, wt %: Cu 32.23, Fe 1.14, Cl 16.13, H 3.1, N 29.9, C 12.2, Î 3.4, total 98.1. The empirical formula is (Z = 4): Cu_1.92Fe_0.08Cl_1.72N_8.09C_3.85H_11.66O_0.81. The structural model was obtained using the single-crystal X-ray diffraction data (R_F = 0.1627). Chanabayaite is orthorhombic, space group Imma, a = 19.484(3), b = 7.2136(10), c = 11.999(4) Å, V = 1686.5(7) ų, Z = 2. In chanabayaite, chains of the corner-sharing Cu(l)-centered octahedrons and single Cu(2)-centered octahedrons are connected via 1,2,4-triazolate anions (C²N₃H₂)^–. NH₃ and Cl^– are additional ligands coordinating Cu²⁺. Chanabayaite is a transformational mineral species formed as a result of leaching Na and one third of Cl and partial dehydration of the protophase Na₂Cu₂Cl₃(N₃C₂H₂)₂(NH₃)₂₄H₂O. Strongest lines of the X-ray powder diffraction pattern [d, Å (I, %) (hkl)] are: 10.19 (100) (101), 6.189 (40) (011), 5.729 (23) (301), 5.216 (75) (211, 202), 4.964 (20) (400), 2.830 (20) (602, 413, 503), 2.611 (24) (123, 422, 404).

Key words: chanabayaite, Pabellon de Pica, Tarapaca, Chile, guano, new mineral, metal organic mineral, triazolate, ammine, crystal structure.