Condensation of cometary silicate dust using an induction thermal plasma system I. Enstatite and CI chondritic composition

TL;DR

This study investigates the formation of GEMS in interplanetary dust by experimentally condensing silicate and chondritic gases in plasma, revealing potential precursor particles with embedded metal nanoparticles.

Contribution

It demonstrates the synthesis of GEMS-like amorphous silicate particles with metallic cores through plasma condensation experiments, providing insights into their formation process.

Findings

Amorphous Mg-silicate particles were successfully condensed.

Particles embedded with Fe-Ni nanoparticles resemble GEMS.

Condensation conditions influence particle size and composition.

Abstract

Glass with embedded metal and sulfides (GEMS) is a major component of chondritic porous interplanetary dust particles. Although GEMS is one of the most primitive components in the Solar System, its formation process and conditions have not been constrained. We performed condensation experiments of gases in the system of Mg-Si-O (MgSiO3 composition) and of the S-free CI chondritic composition (Si-Mg-Fe-Na-Al-Ca-Ni-O system) in induction thermal plasma equipment. Amorphous Mg-silicate particles condensed in the experiments of the Mg-Si-O system, and their grain size distribution depended on the experimental conditions (mainly partial pressure of SiO). In the CI chondritic composition experiments, irregularly shaped amorphous silicate particles of less than a few hundred nanometers embedded with multiple Fe-Ni nanoparticles of ~<20 nm were successfully synthesized. These characteristics are very similar to those of GEMS, except for the presence of FeSi instead of sulfide grains. We propose that the condensation of amorphous silicate grains smaller than a few tens of nanometers and with metallic cores, followed by coagulation, could be the precursor material that forms GEMS prior to sulfidation.