Jadeite and related species in shocked meteorites: Limitations on inference of shock conditions

Abstract Jadeite is frequently reported in shocked meteorites, displaying a variety of textures and grain sizes that suggest formation by either solid-state transformation or crystallization from melt. Some-times, jadeite has been identified solely on the basis Raman spectra. Here we argue additional characterization needed to confidently identify distinguish it related species. Based chemical spectral analysis three new occurrences, complemented first-principles calculations, show pyroxenes space (Na)M2(Al)M1(Si2)TO6–(Ca)M2(Al)M1(AlSi) TO6–(☐)M2(Si)M1(Si2)TO6 with up 2.25 atoms Si per formula unit have features similar jadeite. However, their distinct stability fields (if any) synthesis pathways, considered together textural constraints, different implications for precursor phases estimates impactor size, encounter velocity, crater diameter. A reassessment occurrences casts light many previous conclusions about shock histories preserved particular meteorites.