Infrared absorption chlorites

Hayashi, H. and Oinuma, K. (1965) Relationship between infrared absorption spectra in the region of 450-900 cm and chemical composition of chlorite. Am. Mineral, 50, 476-483. 

The minerals found in United States coals continue to be studied with the availability of improved instrumental procedures such as x-ray diffraction, infrared absorption, and scanning electron microscopy beyond the traditional optical and chemical mineralogical techniques as applied to thin sections, polished pellets, and isolated particles. The minerals may be grouped into the silicates (kaolinite, illite montmorillonite, and chlorite), the oxides (quartz, chalcedony, hematite) the sulfides (pyrite, marcasite, and sphalerite) the sulfates (jarosite, gypsum, barite, and numerous iron sulfate minerals) the carbonates (ankerite, calcite, dolomite, and siderite) and numerous accessory minerals (apatite, phosphorite, zircon, rutile, chlorides, nitrates, and trace minerals). 

Tuddenham and Lyon [1959] state that the amount of substitution of A1 for Si and the total iron content of natural chlorites can be determined from the infrared absorption bands in the 9.0 to 10.5 jtt region (Si-0 stretching band). The amount of tetrahedral substitution is estimated from the number and the shapes of the bands in this region. The total Fe content is measured from the position of the maximum absorption band in the same region. The 7 A aluminian serpentines of similar composition can be recognized by the presence of absorption bands in the 2.7 to 2.8 region (0-H stretching band) that are either very weak or not present in true chlorites. 

Kodama, H., and K. Oinuma, 1963. Identification of kaolin minerals in the presence of chlorite by X-ray diffraction and infrared absorption spectra. Clays Clay Min, Proc. 11th Conf. New York Pergamon Press, pp. 236-249. 

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