Optical spectra of chromium, nickel, and cobalt-containing pyroxenes

Spectra have been obtained on synthetic NaCrSi₂O₆ (jadeite type); CaMg_1-xCo_xSi₂O₆, and CaMg_1-xNi_xSi₂O₆ (diopside type); Mg_1-xCo_xSiO₃ and Mg_1-xNi_xSiO₃ (clinoenstatite type). All compounds exhibit spectra characteristic of the transition metal ions in an octahedral field. Only the cobalt compounds have spectra with the expected additional splittings from site distortion. The crystal field parameters Dq and B were calculated for all compounds and were used to show that Ni²⁺ orders on the M₂ site in clinoenstatite while Co²⁺ is predominantly on M(l).