Fig. 7.

Elemental composition studied by electron microprobe. (a) Energy-dispersive x-ray analysis (EDXA) spectrum recorded in a region with low levels of Zn. The halogens Br and I are present in considerable quantities; there is also some Cl. (b) EDXA spectrum from a region rich in Zn. With increasing Zn concentration, the Cl concentration considerably increases, whereas the Br and I concentrations tend to decrease. (c) Local Cl concentration plotted against local Zn concentration. The occurrence of the two elements is highly correlated, and the data appear to lie on a straight line. •, Data from the jaw tip; ○, data from the middle part of the jaw, containing less Zn.