gems, garnet, almandine, pyrope-almandine, pyrope, rhodolite, analytical, species

Lind, Henn, and Milisenda distinguish three types of rhodolite garnet through visible absorption spectroscopy, relating their colours to differences in chemical composition. Type I, exemplified by material from Naktamunda, Orissa, India, transmits strongly in both the blue-violet and red regions, producing a pronounced blue-violet purple colour. Type II, represented by rhodolites from the Arusha region of Tanzania, has lower blue-violet transmission and consequently appears more reddish purple, ranging from wine red to raspberry. Type III, exemplified by Kangala material from Tanzania, exhibits additional absorption associated with manganese, chromium, and vanadium. Its colours may approach those of Malaya garnets, while some specimens change from purplish red under incandescent illumination to greenish blue in daylight. The classification provides a framework for explaining colour variation among rhodolites from different sources.