X-ray spectra of iron atoms in minerals

Abstract

The results of X-ray fluorescence Ka _1,2 and Kβ₁,β′-spectra of iron in 54 samples, including 23 minerals, are presented. Spectrum characteristics are mainly dependent on the environment of iron in the sample, the most susceptible parameter being the chemical shift δβ₁. For the compounds investigated δβ₁ varies between −1.58 eV and +1.56 eV when referring to metallic iron. Chemical shifts of compounds with predominantly covalent bonds exhibit more negative values, compounds with metallic bonds nearly vanishing values and compounds with predominantly ionic bonds more positive values. The FeKβ₁,β′-group of lines is actually a superposition of three lines: the long-wave line β′ and two overlapping lines β ⁵₁ and β ⁷₁ of which the superposition is conventionally denoted as β₁. The relative intensity of β ⁵₁ increases with ionicity of the bond, while that of β ⁷₁ decreases. The effective charge of iron has been determined for a group of iron-bearing minerals.