Lunar plagioclase - A mineralogical study.

Abstract

Mineralogica l pro perties of calcic plagioclase have been analyzed using U-stage, microprobe, x-ray precession cameras, and a 650 kY electron microscope.The o rienta tion of the optical indicatrix in lun ar and eucrite anorth ites is described with Euler a ngles.All crystals, except one, show strong band diffuse c-reflections in precession photographs.In 10017, b-split-reflection s have been found .Dark-field electron microgra phs of 143 \0 anorthite show both large a nd small b-antiphase domain s, and an ex-.solution structure in crystals that display b-split reflections in the diffractogram.Diffuseness of c-refiections in x-ray photographs and the in ability to resol ve c-domains in electronmicrographs in An 94 anorthite of 14310 indicate rela tively rapid cooling of thi s rock compared to plutonic rocks..