Volborthite occurrence at the Alaid volcano (Atlasov Island, Kuril Islands, Russia)

Zhitova E. S., Anikin L. P., Sergeeva A. V., Ismagilova R. M., Rashidov V. A., Chubarov V. M., Kupchinenko A. N.

Zapiski RMO (Proceedings of the Russian Mineralogical Society). 2020. V. 149. N 3. P. 78-95

https://doi.org/10.31857/S0869605520030119

Language: Russian

Abstract

Yellow volborthite, Cu_2.95(V_1.91P_0.09)_Σ2O₇(OH)_1.90 ·2H₂O, and turquoise-coloured atacamite, Cu₂[Cl_0.98(OH)_0.02]_Σ1.00(OH)₃, have been found incrusting cracks and the surface of lava blocks located at the North-East slope of the Alaid volcano (Atlasov island, Kuril islands, Russia). The Raman spectrum of volborthite contains the following bands in the range 900-70 cm^-1 (with assignment): 885 (ν₁ VO₄), 809 (ν₃ VO₄), 748 (ν₃ VO₄, libration mode of water, deformation mode of OH), 507 (ν₄ VO₄, ν₁ CuO₆), 471 (ν₄ VO₄, ν₁ CuO₆), 441 (ν₄ VO₄, ν₂ CuO₆), 345 (ν₂ VO₄), 257 (v₅ CuO₆, ν₂ VO₄) and 241 (ν₂ VO₄) cm^–1. At Alaid volborthite is likely a supergene mineral formed as a result of alteration of primary fumaroles minerals. Euchlorine and shcherbinaite could be as sources of Cu and V, respectively. On the other hand, the volborthite-atacamite paragenesis could form in the near-surface relatively low-temperature zone of fumarole ˗ the so-called zone of “hot hypergenesis” as a result of interaction of primary exhalative minerals with meteor water under the influence of volcanic gas.

Keywords: vanadate, copper, volborthite, atacamite, Raman spectroscopy, paleofumarole,Alaid volcano, Atlasov Island, Kuril Islands