Abstract
The following organic radicals were identified by EPR spectroscopy in apatite from marine phosphorites (granular, nodular, shelly, and microcrystalline), supergene phosphorites (from ocean islands only), and modern and fossil biological materials (human dental enamel, fossil shark teeth, and pathogenic cardioliths): ĊH3, ĊH2-R, HOĊHR,(CH3)2-ĊR,3org, PO32−, P(OR)3, and perinaphtðenyl. Each textural and petrographic type of apatite corresponds to a specific model of organic radicals, which correlates with the type of organic matter (sapropelic, humic, guano, or collagen). The latter is controlled by the conditions of mineral formation, including climatic ones, and postdiagenetic (catagenetic) processes. A relationship was established between the EPR spectra of observed organic radicals and the valence state and structural position of impurity ions: (1) vanadium: V4+ (VO2+) in the Ca2+ II site or V5+ (VO4)3− → (PO4)3− and (2) uranium: U4+(UO2) in the Ca2+ II site or U6+ chemisorbed on the surface as UO22+
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