ALUMINUM ABUNDANCES IN STONY METEORITES

Aluminum abundances have been measured via nondestructive instrumental neutron activation analysis in some 120 meteorites and minerals. Average Al abundance values reported in this work are less, in general, than those reported previously and are considered more accurate. Moreover, the observed Al standard deviation dispersions of 6 %, 7 % and 6 %, respectively, in the chemical-petrologic classes of H4-6, L4-6 and LL4-6 meteorites are considerably less than earlier (chemical) dispersion values of 25 %, 28 % and 28 %, respectively. The average Al Si atomic ratio of 0.087 is nearly the same for the three classes of carbonaceous ohondrites and is distinctly different from a ratio of 0.061 observed in ordinary chondrites. Furthermore, the Al Na ratio increases progressively from 1.42, 2.40 to 3.29 for the three classes of carbonaceous ohondrites C1, 2 and 3. Al Na ratios are uniform in ordinary chondrites and average 1.45. We observe no significant linear correlation between the Al and Fe abundance of most of the meteorites, thus raising questions about events in the past history of the meteorites. © 1969.