J. Phys. IV France 7 (1997) C2-615-C2-616
XAFS Studies of Iron in the Teeth of Chiton, Acanthopleura JaponicaC. Numako1 and I. Nakai2
1 Faculty of Integrated Arts and Sciences, Tokushima University, Minami-josanjima 1-1, Tokushima 770, Japan
2 Department of Applied Chemistry, Faculty of Science, Science University of Tokyo, Kagwazaka, 1-3, Shinjuku 162, Japan
The variation of iron chemical forms during the teeth formation of chiton, a well-known iron accumulator, was clarified by utilizing the fluorescence XAFS technique. Fe K-XANES spectra of the teeth of chiton in various maturation stages show a complex oxidation/reduction process of iron during the teeth formation. In the earliest stage of the maturation, an amorphous feiritin-Ske ferric compound accumulates in the framework of the organic substances. Magnetite formation occurs abruptly in the next maturation stage, and the color of the teeth changes from reddish brown to gray. The spectra of the teeth in the latter maturation stages show that the edge-energy is higher than that of magnetite and their pnt-edge peak height are lower than that. These results suggest that the fully mineralized teeth are considered to be a mixture of magnetite and a ferric compound and the contest erf magnetite decreases with the maturation of teeth.
© EDP Sciences 1997