English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

A martian basalt (Yamato 980459) composition was used to synthesize olivine, spinel, and pyroxene at 1200 °C at five oxygen fugacities: IW-1, IW, IW+1, IW+2, and QFM. The goal of this study is to examine the significant variation in the value of DV  pyroxene/melt  with changing Wo content in pyroxene. While most literature on this subject relies on electron microprobe data that assumes that if the Wo component (CaSiO 3 ) is &lt;4 mol%, the pyroxene is in fact orthopyroxene, we’ve made a more robust identification of orthopyroxene using appropriate Kikuchi diffraction lines collected during electron backscatter diffraction analysis. We compare augite (Wo  ~  33), pigeonite (Wo  ~  13), orthopyroxene (Wo &lt;4), and olivine. In augite (Wo  ~  33), the M2 site is 8-coordinated, while in pigeonite (Wo  ~  13), the site is 6-coordinated. The larger (8-coordinated) M2 site in augite requires structural expansion along the chain direction. The longer chain is enabled by the substitution of the larger Al for Si. The Al 3+  substitution for Si 4+  causes a charge deficiency that is made up, in part, by the substitution of V 4+  and V 3+  in the pyroxene M1 site. This rationale does not fully explain the dramatic decrease in DV  orthopyroxene/melt . In monoclinic pyroxenes, the TOT stacking is characterized by + + + + (indicating the direction), a stacking pattern that produces a monoclinic offset. In orthopyroxene, the stacking is + + - -, which produces an orthorhombic structure. The M2 site is located between the reversed TOT units and is highly constrained to 6-coordination and thus cannot contain significant Ca that requires 8-coordination. Because the M2 site in orthopyroxene is small and constrained, it accommodates less Al in the tetrahedral chains and thus less V in the pyroxene M1 site.

american mineralogist

Valence state partitioning of V between pyroxene and melt for martian melt compositions Y 980459 and QUE 94201: The effect of pyroxene composition and crystal structure