Trace elements in 59 mostly highland moon rocks

Abstract

New chemical analyses for up to 26 trace elements, including seldom-determined highly siderophile elements Ir, Os, Re, Au, Pd, and Ge, for 59 lunar samples are reported. Most of these samples are polymict breccias from Apollo 16. Remarkably few have Group 7 (extremely low Au/Ir) meteoritic components. Several samples have uncommonly high Au/(Ir + Re) ratios, even higher than group 1L. Volatile-element enrichments are found in several fragments from rusty rock 66095. A matrix sample from fragmental breccia 60639 shows Cd and In enrichments, also observed previously in samples of anorthosite and mare basalt from the same breccia. Evidently, for these highly labile elements, chemical exchange has affected clasts that for most other elements are pristine.