title: Mossbauer effect and high-voltage electron microscopy of pyroxenes in type B samples.
abstract: Site occupancy numbers for ferrous iron, magnesium, and calcium at the Ml and M2 sites in lunar clinopyroxenes are estimated from nuclear gamma-ray resonant absorption spectra of (57)Fe. The cation distribution is ordered; calcium and magnesium prefer M2 and Ml, respectively. The distribution corresponds to an equilibrium at a temperature lower than 680 degrees C. Crystals cleaved and sectioned by diamond-knife ultramicrotomy were examined by high-voltage (200 kv) electron microscopy and diffraction. Uniform 300-to 600-A-wide bands that correspond to single crystal domains were found. Correlation of the bands with magnetic ordering at low temperatures is considered.
authors.forename: H
authors.initials: H
authors.lastname: Fernández-Morán
authors.forename: S S
authors.initials: SS
authors.lastname: Hafner
authors.forename: M
authors.initials: M
authors.lastname: Ohtsuki
authors.forename: D
authors.initials: D
authors.lastname: Virgo