Vibration Spectrum Characteristic of Gem-Grade Tinticite from Ma'anshan, Anhui Province

Tinticite, which is associated with and has a similar appearance of turquoise was found in the turquoise mining area in Ma'anshan, Anhui Province, China. It has earthy to waxy luster, opaque, fine structure, and easy to absorb water. Generally it has light yellowish green to greenish yellow colour. Compared with turquoise, it has lower hardness with similar structure. Gem microscope, refractometer, Fourier transform infrared spectrometer, Raman spectrometer, X-ray powder diffractometer and UV-Visible spectrophotometer were used to identify the mineral components and spectral characteristics of tinticite. The results show that its main mineral compoment is tinticite with a small amount of turquoise and jarosite, which has rarely been reported in previous studies. The infrared spectrum of tinticite is mainly represented by the characteristic peak near 3 390 cm^-1 caused by the stretching vibration of OH, the 1 630 cm^-1 peak caused by the bending vibration of crystal water, and 1 129, 1 110, 1 064, 1 019, 961, 877, 760 cm^-1 characteristic peaks caused by stretching vibration of PO₄^3-. Raman spectrum analysis detect that the Raman shifts at 1 091, 1 018 cm^-1 and 556 cm^-1 of tinticite are caused by the stretching vibration of PO₄^3-. The samples can be identified quickly and effectively in the laboratory according to their main mineral component characteristics, infrared absorption spectrum, Raman spectrum characteristics, etc.