Pyroxenes are among the most common minerals in the solar system and are ideally suited for remote geochemical analysis because of the sensitivity of their distinctive spectra to mineral composition. Fe is responsible for the dominant pyroxene absorptions in the visible and near-infrared, but substitutions of other cations such as Ca change the crystal structure and site geometries and thus the...

Introduction: Traditionally, the diogenite meteorites have been viewed as orthopyroxenite cumulates with small amounts of olivine [1]. Several olivine-rich, harzburgite diogenites have recently been recognized and may provide insight into the occurrence of olivine on Vesta and in the HED meteorite suite [2,3]. In both the harzburgite and orthopyroxenite diogenites, olivine has been interpreted ...

The first observation of the vibrational spectrum of the synthetic pyroxene Li-kosmochlor (LiCrSi2O6) is reported herein. The Raman and visible spectra are reported as a function of pressure. Though the pyroxene retains its P21/c symmetry, changes in the Raman spectra are observed between 6.8 and 7.7 GPa, possibly due to the formation of an additional bond between Li and O3 or some other transi...

Calcium Tschermak’s pyroxene (CaTs), CaAlAlSiO6, is well known as an important component in pyroxene. It is a member of the Ca clinopyroxene group in which Al dominates in the M1 site. Pyroxenes with more than 80 mol% CaTs were observed previously in Ca-,Al-rich refractory inclusions (CAI) from five carbonaceous chondrites. This study re-investigated the near end-member CaTs in the Allende and ...

In the present work, the non-spherical dust grain characteristics of comet Levy 1990XX with different silicate grain compositions (both pyroxene and olivine) are studied using the T-matrix method. Considering amorphous pyroxene grain (MgxFe1−xSiO3) with x (= 0.4, 0.5, 0.6, 0.7, 0.8, 0.95, 1) and amorphous olivine grain (Mg2yFe2−2ySiO4) with y (= 0.4, 0.5) (Dorschner et al. 1995), the observed p...

A STUDY OF TRACE-ELEMENT PARTITIONING BETWEEN PYROXENE AND ANGRITIC MELT: EQUILIBRIUM AND KINETIC EFFECTS INCLUDING SECTOR ZONING IN PYROXENE. G. E. Lofgren 1, A. J. Fahey2, and G. J. Wasserburg2, 'Mail Code SN4, NASA Johnson Space Center, Houston TX 77058, USA, 2Lunatic Asylum, Division of Geological and Planetary Science, Mail Stop 170-25, California Institute of Technology, Pasadena CA 91125...