Abstract

We present a comparative analysis of powder infrared spectra of cancrinite-group minerals with the simplest framework, of AB type, from the viewpoint of crystal-chemical characteristics of extra-framework components. We provide IR spectra for typical samples of cancrinite, cancrisilite, kyanoxalite, hydroxycancrinite, depmeierite, vishnevite, pitiglianoite, balliranoite, davyne and quadridavyne, as well as the most unusual varieties of cancrinite-subgroup minerals (Ca-deficient cancrinite, H2O-free cancrinite, intermediate members of the series cancrinite – hydroxycancrinite, cancrinite–cancrisilite, cancrinite– kyanoxalite, K-rich vishnevite, S2-bearing balliranoite). Samples with solved crystal structures are used as reference patterns. Empirical trends and relationships between some parameters of IR spectra, compositional characteristics and unit-cell dimensions are obtained. The effect of Ca content on stretching vibrations of CO32− is explained in the context of the cluster approach. The existence of a hydrous variety of quadridavyne is demonstrated.

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