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Reflectance Spectroscopy Characteristics of Turquoise.

Authors :
Jun-Ting Qiu
Hui Qi
Ji-Lin Duan
Source :
Minerals (2075-163X). 2017, Vol. 7 Issue 1, p3. 10p.
Publication Year :
2017

Abstract

In this study, we determined the reflectance spectra of four types of turquoise with different hardness (porcelain, hard turquoise, soft turquoise, and loose turquoise) using an ASD™ TerraSpec spectrometer (spectral range 350-2500 nm, Visible-Near Infrared, and Short-wave Infrared). Several absorption features, including six narrow absorption peaks at 425 nm, 1480 nm, 2160 nm, 2218 nm, 2253 nm, and 2347 nm, and three wide peaks between 625-756 nm, 756-915 nm, and 1885-2133 nm have been identified. The strength of the absorption of turquoise increased with decreasing hardness. The absorption peaks at 2160 nm, 2218 nm, 2253 nm, 2347 nm, and 1885-2133 nm on some turquoise spectra (porcelain spectra, for example) were relatively weak, while those at 425 nm, 1480 nm, 625-756 nm, and 756-915 nm were always observed on all turquoise spectra, which could be the diagnostic absorption features for turquoise. Additionally, the hyper-spectral imaging (spectral range 1000-2500 nm, Short-wave Infrared) of the four types of turquoise were obtained using a HySpex™ imager. The Spectral Angle Mapper (SAM) method was successfully used to recognize turquoises, suggesting that hyper-spectral imaging may serve as a useful tool for fast turquoise identification and separation, especially for massive turquoise samples. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
2075163X
Volume :
7
Issue :
1
Database :
Academic Search Index
Journal :
Minerals (2075-163X)
Publication Type :
Academic Journal
Accession number :
121018189
Full Text :
https://doi.org/10.3390/min7010003