YU Yun-feng1, LIAO Jia1*, WU Gai2,3
(1. Gem Center, Chengdu Institute Product Quality Inspection Co. Ltd, Chengdu 600041, China;
2.Gemmological Institute, China University of Geosciences, Wuhan 430074,China; 3. School of Earth Sciences, China University of Geosciences, Wuhan 430074,China )
Abstract:A kind of gem product with business name “Hongbishi” appears in the jewelry market in recent years. Usually, “Hongbishi” is sold as the imitation of Nanhong, a kind of red agate with hematite inclusions, for the similar appearance, especially the high saturated orange-red color. In this paper, gemological characteristics and mineral components of “Hongbishi” samples are investigated. The experimental methods include conventional gemological methods, infrared spectrum, laser Raman spectrum and X-Ray diffraction, and UV-Vis-NIR spectrum analysis. Results show that the vitreous luster (from weak to middle), refractive index (between 1.53 and 1.54, point measurement) and hardness (between 6 and 7 on the Mohs’ scale) of “Hongbishi” are similar to quartzite jade. It is hard to distinguish “Hongbishi” from “Nanhong” or other quartzite jades only according to the conventional gemological methods. Based on the experimental data of infrared spectrum, laser Raman spectrum and X-Ray diffraction, quartz is the dominant mineral component, while hematite and andradite are minor. In addition, the existence of molecule water and -OH inside can be confirmed by the absorption peaks at 5166－5200 cm-1 and 4322 cm-1 in NIR spectrum. In UV-Vis-NIR spectra with first order derivative, all of “Hongbishi” samples show the absorption centered on 576 nm, indicating the coloration results from hematite inside.
Keywords: Hongbishi; Gemological Characteristics; Spectral Characteristics; Mineral Component；first order derivative spectrum
ACTA MINERALOGICA SINICA Vol. 37, No. 6, 2017, Page 801-806
