A near-infrared and Raman spectroscopic study of the mineral richelsdorfite Ca2Cu5Sb[Cl|(OH)6|(AsO4)4]·6H2O

Abstract

Raman spectroscopy has enabled insights into the molecular structure of the richelsdorfite Ca(2)Cu(5)Sb[Cl|(OH)(6)|(AsO(4))(4)]·6H(2)O. This mineral is based upon the incorporation of arsenate or phosphate with chloride anion into the structure and as a consequence the spectra reflect the bands attributable to these anions, namely arsenate or phosphate and chloride. The richelsdorfite Raman spectrum reflects the spectrum of the arsenate anion and consists of ν(1) at 849, ν(2) at 344 cm(-1), ν(3) at 835 and ν(4) at 546 and 498 cm(-1). A band at 268 cm(-1) is attributed to CuO stretching vibration. Low wavenumber bands at 185 and 144 cm(-1) may be assigned to CuCl TO/LO optic vibrations.

A vibrational spectroscopic study of philipsbornite PbAl3(AsO4)2(OH)5⋅H2O-molecular structural implications and relationship to the crandallite subgroup arsenates

“…Indeed, Raman spectroscopy has proven most useful for the study of diagenetically related minerals as often occurs with minerals containing arsenate and sulphate groups, including philipsbornite and crandallite. Raman spectroscopy is especially useful when the minerals are X-ray non-diffracting or poorly diffracting and very useful for the study of amorphous and colloidal minerals [20][21][22][23][24][25][26][27][28][29]. Philpsbornite is a mineral which falls into this category.…”