Introduction: Enstatite whiskers (<10 µm length, <200 nm width) occur in chondritic-porous interplanetary dust particles (CP IDPs) [1], an Antarctic micrometeorite [2] and a comet 81P/Wild-2 sample [3]. The whiskers are typically elongated along the [100] axis and contain axial screw dislocations, while those in terrestrial rocks and meteorites are elongated along [001]. The unique crystal morp...

Introduction: The two groups of enstatite chondrites (EH and EL) and aubrites, their differentiated counterparts, are a unique suite of specimens that formed under highly reducing conditions within the solar nebula, possibly on three separate parent bodies [1]. The reduced nature of the meteorites is shown by their unusual mineralogy, characterised by the presence of abundant sulphides. They al...

A suite of 47 carbonaceous, enstatite, and ordinary chondrites are examined for Re-Os isotopic systematics. There are significant differences in the Re/Os and Os/Os ratios of carbonaceous chondrites compared with ordinary and enstatite chondrites. The average Re/Os for carbonaceous chondrites is 0.392 0.015 (excluding the CK chondrite, Karoonda), compared with 0.422 0.025 and 0.421 0.013 for or...

Ten reversed brackets of aqueous silica concentration in equilibrium with enstatite (Mg2Si2O6) and forsterite (Mg2SiO4) were determined at 700 to 900°C and 4.35 to 14 kbar. Silica solubilities were measured by a weight loss-weight gain method and by approaching equilibrium from higher and lower silica concentrations. Both single-crystal and fine-grained synthetic enstatite and forsterite starti...

The mechanical properties of steatite ceramics after high-temperature processing depend on inversion of high-temperature Mg2Si2O6 protoenstatite polymorph to low clinoor ortho-enstatite, which are characterized by Raman spectroscopy. The Raman spectrum of a pure Mg2Si2O6 protoenstatite is sufficiently distinct from those of low clinoand ortho-enstatite to allow rapid identification in a bulk sa...

[1] The behavior of synthetic-powdered 57Fe-enriched enstatite (Mg0.980Fe0.020(5))(Mg0.760Fe0.240)Si2O6 has been explored by X-ray diffraction (XRD) and nuclear resonant inelastic X-ray scattering (NRIXS). The Pbca-structured enstatite sample was compressed in fine pressure increments for our independent XRD measurements. One structural transition between 10.1 and 12.2 GPa has been identified f...

Introduction: Enstatite chondrites have remarkable properties: they were formed in a reducing environment, they are putatively similar to precursor material of Earth, Venus, or Mercury, have a terrestrial oxygen isotopic composition and an uncommon noble gas signature [1-5]. Trapped noble gases in Echondrites are intermediate between solar and chondritic composition and consist of two component...

New shock wave data for Bamle enstatite (Mgo. s•,Feo.•JSiOs in the range from 60480 kb indicate a Hugoniot elastic limit of 67 ñ 10 kb and a possible phase-transition-produced shock front of 135 _ 10 kb amplitude. Above the latter shock pressure, states in a mixedphase regime are achieved up to •350 kb, above which the Hugoniot states are believed to represent the equation of state of a shock-i...