Mineral identification and geological mapping using near-infrared spectroscopy analysis

Abstract

In recent years, the near-infrared spectroscopy measurement technology in China has made considerable progress; it has been widely used in the fields of agriculture, chemistry, geology, and medicine measurement. The near-infrared spectroscopy is very sensitive to the characteristics of C-H (methyl, a methylene group, a methoxy group, a carboxyl group, an aryl group, etc.), hydroxy O-H, mercapto S-H, and amino N-H. So, it can distinguish the crystallinity of single mineral (clay minerals, chlorite, serpentine, etc.), containing hydroxy silicate minerals (epidote, amphibole, etc.), sulfate minerals (alunite, pyritepotassium alum, gypsum, etc.), and carbonate minerals (calcite, dolomite, etc.) in the layered silicate. The character of near-infrared spectroscopy is one of the important guarantees for the instrument development of the small portable near-infrared mineral analyzer, and for its fast, accurate identification of rock samples. In this paper, we focus on the near-infrared spectral characteristics, identification method, and quantitative analysis method for the low-temperature alteration minerals; at the same time, a portable near infrared spectrometer and its principle were presented. In the experiment, spectral parameters were acquired from the characteristic spectra of altered minerals, and the relationship between altered minerals and ore-forming were established. The measured spectral data from the drilling rock cores in Zijinshan Mine in Fujian province was used as an example to illustrate the credibility of the proposed method.