Gemological and Chemical Characterization of Gem-Grade Peridot from Yiqisong, Jilin Province

Peridot has a long history and is deeply loved by people for its unique olive-green color. The Yiqisong peridot deposit in Jilin Province is a newly discovered peridot deposit that still deserves systematic research. In this study, gemological and chemical analyses of thirty-three Yiqisong peridot samples were carried out to investigate the gemological characteristics, as well as the mantle properties and formation conditions of the Yiqisong. In addition, we identified gemological differences in peridot between Yiqisong, Tanzania, and Arizona. The Yiqisong peridot samples have typical peridot gemological characteristics. The UV–visible spectrum indicated that Fe is the chromogenic element. The infrared spectra and Raman spectra of different samples are consistent, which indicates that the Yiqisong peridot belongs to forsterite. The contents of Ni and V in Yiqisong peridot are generally low, distinguishing it from peridot found in Tanzania and Arizona. The major and trace elements of samples show that the Yiqisong peridot is derived from the spinel lherzolite xenoliths with the P–T formation conditions of 813–1087 °C and 21–22 kbar. The Yisqisong peridot samples have relatively high Fo values (up to 91.6), supporting their origin from a moderate refractory lithosphere mantle. Therefore, this study provides gemological, mineralogical, and chemical evidence that fills the research gap in peridot deposit studies and lays the foundation for follow-up investigations of gem-grade peridot deposits.