Optical properties of a new decorative stone—rayizite

Abstract

In this paper, we present the findings of research on absorption spectra, reflection spectra, and luminescence spectra for a new decorative stone—rayizite, which is a mixture of antigorite, dolomite, and a small amount of talc. This stone exhibits the alexandrite effect, and the color is due to chromian antigorite. The Y and U bands in the absorption spectra and the R line at 686.6 nm in the luminescence spectra indicate that Cr3+ ions are present. The emission spectrum also includes the emission of Fe2+ ions at wavelength 615 nm. The band at 650 nm, which becomes active under the action of a pulsed electron beam and does not occur during photoexcitation, is a distinguishing feature. This band belongs to a center associated with emission from nonbridging oxygen. In this paper, we discuss the mechanism for the formation of such luminescence centers.