Compression moduli of Cr3+-centered octahedra in a variety of oxygen-based rock-forming minerals

High-pressure electronic absorption spectra at room temperature and at pressures 10−4 ν˜[cm−1]>12820) on analysed single crystal slabs, about 20 μm thick, of Cr3+-bearing spinel (I), kyanite (II), corundum (III), pyrope (IV) and uvarovite (V) using DAC-cell techniques in combination with single-beam microscopespectrometry. Ligand field theoretical evaluation of the spectra yielded following results: