Cadmium abundances in meteoritic and terrestrial matter

Abstract

Abundances of cadmium have been determined by neutron-activation analysis in 31 meteorites: 0.52–1.16 p.p.m. in five carbonaceous chondrites; 0.015–0.12 p.p.m. in six ordinary bronzitic and hypersthenic chondrites 0.042–3.3 p.p.m. in three enstatitic chondrites; 0.022 and 0.065 p.p.m. in two eucritic achondrites; 0.18 and 1.79 p.p.m. in two nakhlitic achondrites; ≤ 0.010 and 0.33 p.p.m. in two calcium-poor achondrites; < 0.004 and 0.056 p.p.m in two mesosiderites; 0.13 and 0.33 p.p.m. in two pallasites; 0.0085 to 0.056 p.p.m. in seven iron meteorites. An atomic abundance of Cd/10 6 Si atoms of 1.8 ± 0.6 is calculated for five carbonaceous chondrites, which agrees well with the solar value of 1.5 given by Aller (1962). Cadmium abundances in two terrestrial basalts were 0.33 and 0.5 p.p.m. and 0.026 and 0.24 p.p.m. in two deepseated eclogites. Abundances of cadmium and other chalcophilic elements are discussed in terms of chondritic parent models. Low fractional abundances in the earth's crust of the chalcophilic elements cadmium (0.00085), zinc (0.0014), bismuth (0.0045), and thallium (0.33), corroborate the conclusions reached by Gast (1960), either that the earth's original composition was not chondritic-like, or that elements like the alkalis (and the chalcophilics) reside below the crust.