Raman study of several Cu‐bearing complex minerals from the guano deposit at Pabellón de Pica, Tarapaca region, Chile

Abstract

Pabellón de Pica, Tarapaca, Chile, is a former guano mine exploited in the late 19th and early 20th centuries. Guano is in a direct contact with Cu sulfide mineralization leading to the formation of minerals with a highly unusual chemical composition, especially Cu‐organic complexes and nitrogen‐bearing phases. In this work, we report results of the Raman spectroscopic investigation of several unique Cu‐bearing minerals that are the result of supergene processes at the Pabellón da Pica site. We focus on several minerals with new and interesting structure types which were described from this locality for the first time, namely, antipinite (K–Na–Cu oxalate), ammineite (Cu ammine complex), chanabayaite (Cu ammine triazolate complex), and joanneumite (Cu isocyanurate). The Raman spectra contain specific bands attributed to the characteristic vibrations of the molecular groups present in the minerals (oxalate, ammine, triazolate, and isocyanurate groups) and vibrations within Cu‐centered polyhedra. A comparison was made with the vibrational spectra of related minerals and synthetic phases, which revealed substantial proliferation and shifting of numerous bands, which is in agreement with the complex composition of the investigated minerals. The results obtained appropriately complement known structural and spectroscopic data published previously.

Zn(NH3)2Cl2, a Mineral-like Anthropogenic Phase with Ammine Complexes from the Burned Dumps of the Chelyabinsk Coal Basin, South Urals, Russia: Crystal Structure, Spectroscopy and Thermal Evolution

“…In general, the spectrum obtained for Zn(NH 3 ) 2 Cl 2 has many similarities with the spectrum described for ammineite, CuCl 2 (NH 3 ) 2 (see Table S2 for details), which also contains ammine complexes [27]. The most intense modes of the spectrum correspond to the stretching vibrations of the NH 3 groups and Zn-N and Zn-Cl stretching and bending vibrations (Figure 2).…”

“…The bands at <200 cm −1 can be assigned to lattice modes. The intense band at 281 cm −1 is probably connected with the symmetric stretching vibrations (ν s ) of zinc-halogen (Zn-Cl), whereas the band at 417 cm −1 corresponds to the ν s Zn-N vibration modes [27,28]. The medium intense bands at 633 cm −1 and 682 cm −1 are connected with rocking vibration modes of NH 3 .…”

GeoRaman 2022

“…Raman spectroscopic studies dedicated to reporting new spectra of minerals have traditionally been represented in many GeoRaman special issues. In current edition, several Cu-bearing complex minerals from the guano deposit at Pabell on de Pica, Tarapaca region, Chile, were studied by Košek et al 1 A highly unusual chemical composition of the phases is due to the guano being in a direct contact with Cu sulfide mineralization leading to the formation of exotic minerals, namely: antipinite (K-Na-Cu oxalate), ammineite (Cu amminecomplex), chanabayaite (Cu ammine triazolate complex) and joanneumite (Cu isocyanurate).…”