Isomorphism in Vanadinite. 2. IR Spectroscopic Study

Collection of 120 vanadinite, pyromorphite, and mimetite specimens was studied using infrared (IR) spectroscopy. The peculiarities of IR spectra of P- and As-bearing vanadinite are characterized in detail. It is shown that sensitivity of IR spectroscopy to the incorporation of low P content in vanadinite (from 0.1 wt % P2O5) is comparable with that of electron microprobe analysis (EMPA). P-bearing vanadinite can reliably be distinguished from vanadinite and pyromorphite intergrowths (a mechanical mixture) based on the position of bands, which correspond to stretching vibrations of P–O bonds in the IR spectrum. The reason for the band shift, which correspond to V–O and P–O stretching vibrations, including an adjacent position of individual components, in the spectra of P-bearing vanadinite is discussed. None of the studied vanadinite specimens contain (OH)–, (CO3)2–, or H2O groups.