TABLE OF CONTENTS Infrared spectroscopy provides a rapid, simple, and convenient nondestructive means of characteri-zating and identifying minerals. It can readily indicate the presence of specific atomic groupings within the crystal structure. It is probably the best technique for detecting the presence of water in a mineral and for indicating the form in which the water is present. It is also a powerful means of detecting carbonate and of providing clues to the nature of the silicate anion in the mineral structure. Infrared studies are able to detect noncrystalline phases, and some minerals are more easily identified from their IR spectra than from their x-ray diffraction patterns.
Infrared spectroscopy is largely complementary to x-ray diffraction as a tool for the identification of mineral species. The method has the great advantage of x-ray diffraction, however, of being able to detect and characterize noncrystalline compounds, since these absorb as strongly as crystalline material. Moreover, the infrared spectrum points more directly to the general nature of an unknown substance, such information being obtainable from the presence or absence of characteristic absorption bands, as are listed in Tables 23.1 and 23.2. Because the positions of the absorption bands in a spectrum are sensitive to the mass, charge, and bonding characteristics of the constituent ions, infrared spectroscopy can often place a mineral species within the range of compositions over which it exists. In mixtures it may be found that some components are more readily recognized in...
