Abstract

We present high-pressure infrared spectra of two geologically important hydrous minerals: talc, Mg3Si4O10(OH)2 and lawsonite, CaAl2Si2O7(OH)2·H2O,·at room temperature. For lawsonite, our data span the far infrared region from 150 to 550 cm−1 and extend to 25 GPa. We combine our new spectroscopic data with previously published high-pressure mid-infrared and Raman data to constrain the Grüneisen parameter and vibrational density of states under pressure. In the case of talc, we present high-pressure infrared data that span both the mid and far infrared from 150 to 3800 cm−1 covering lattice, silicate, and hydroxyl stretching vibrations to a maximum pressure of 30 GPa. Both phases show remarkable metastability well beyond their nominal maximum thermodynamic stability at simultaneous high-pressure and high-temperature conditions.

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