Gemmological Characteristic of Garnet from Shexian, Hebei Province

Garnet is one of the common jewelry varieties in the jewelry market, which is also an important geological and mineralogical research object. The samples studied in this paper are from Fushan iron ore mine in Shexian, Handan city, Hebei Province, China. The Handan-Xingtai area belongs to Fushan iron ore mine, which is a famous skarn deposit area in China. Fushan iron ore mine was also famous for producing iron ore and idocrase. In this paper, conventional gemmological test, Fourier transform infrared spectroscopy, laser Raman spectroscopy, ultraviolet visible spectroscopy, electron probe test (EPMA), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) were used to investigate the garnet samples from Shexian, Hebei Province. Based on spectroscopical tests and chemical composition analysis, the garnet samples from Shexian is mainly composed of grossularite and it is solid solution of grossularite and almandine. The typical IR transform spectra of grossularite can be observed, and the vibration absorption of structural water (OH^-) is prominent in the functional group region. The Raman spectra of the garnet samples from Shexian are dominated by grossularite and iron occurrence, where Fe³⁺ ion is the main colour origin. The main elements of the samples are Si, Ca, Al and Fe. The grossularite component occupy for over 70% of the component. The crystal formula is (Ca_2.850-2.977, Na_0-0.002, Mn_0.004-0.006, Fe_0.161-0.225²⁺, Mg_0.029-0.047)_3.093-3.176(Cr_0-0.002, Ti_0-0.021, Al_1.402-1.551, Fe_0.102-0.285³⁺)_1.624-1.825Si_3.079-3.156O₁₂.The garnet samples from Shexian, Hebei Province contain more Zr elements than the other producing areas, as well as the distinguishing features.Meanwhile, the rich content Zr of the garnet can be used for the geological origin study.