Olivine annealed up to 1500 C: changes traced by polarised IR reflectance and magnetization

TL;DR

This study investigates how high-temperature annealing up to 1500°C affects natural olivine's spectral, structural, and magnetic properties using IR spectroscopy, X-ray analysis, and magnetization measurements.

Contribution

It introduces a novel spectral analysis method using RGB color assignment to trace phase changes in olivine during high-temperature annealing.

Findings

Olivine undergoes phase changes detectable by IR spectroscopy and magnetization.

High-temperature annealing induces magnetization through Fe-rich oxide formation.

Spectral RGB bands effectively correlate with olivine's phase and magnetic state.

Abstract

Spectral analysis at the infrared (IR) spectral range is introduced with assignment of synthetic red-green-blue (RGB) colours defined by adjustable wavelength and bandwidth. The RGB bands were selected at the phase-specific absorbance A or reflectance R bands of olivine and related materials, which can be formed via high temperature annealing (HTA) of natural minerals up to 1500 C. Natural olivines were collected from quarry at volcanic site in Mortlake, Victoria, Australia and spectrally characterised during IR-THz spectroscopy beamtime experiments at Australian Synchrotron. Phase changes in HTA natural olivines were traced by correlation of optical IR 4-polarisation spectroscopy, X-ray energy dispersive spectroscopy and magnetisation. After HTA, olivine samples were magnetized via precipitation of Fe-rich oxides.