Infrared absorption muscovite

Tateyama H, Shimoda S, Sudo T (1977) Estimation of K-0 distance and tetrahedral rotation angle of K-micas from far-infrared absorption spectral data. Am Mineral 62 534-539 Tillmanns E, Zemann J (1965) Messung des Ultrarot-Pleochroismus von Mineralen. I. Der Pleochroismus der OH-Streckfrequenz in Azurit. N Jb Mineral Mh 1965 228-231 Tsuboi M (1950) On the position of the hydrogen atoms in the crystal structiue of muscovite, as revealed by the infra-red absorption study. Bull Chem Soc Japan 23 83-88 Vedder W (1964) Correlations between infrared spectium and chemical composition of mica. Am Mineral 49 736-768... 

There have been several detailed and careful studies in this field recently. For example. Farmer and Russell [1964] have studied the infrared absorption bands arising from the structural hydroxyl groups of a number of layer silicates, i.e., in the region from 3500 to 3700 cm" . They attempted to assign the two frequencies they observed in terms of either octahedral substitutions or of Al-for-Si substitution tetrahedrally. They confirmed earlier work that in the dioctahedral micas such as muscovite, the OH dipole oscillations lie at around 16° to the plane of the sheets, whereas in the trioctahedral micas, the O—4 bond is normal to the plane of the sheets. 

Rigault, G., and D. Aquilano, 1964. Infrared absorption of muscovite, examination in polarized, transmitted and reflected light. Periodica Mineral. (Rome) 33 445. 

It is not especially in the identification of unknown minerals e.g., in a batch of soil samples) that broad band infrared spectroscopy is at present likely to be useful. The reasons for this are (1) that the main features of infrared spectra of a wide range of minerals e.g.. Si—O or OH bands) are too similar to be used effectively in diagnosis and, (2) that so many factors can affect the detailed shape of the absorption bands that we can very rarely say that, for example, all muscovites (and only muscovites) have this or that detailed feature in their spectra. 

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