Study On Near-Infrared Mineral Spectrometry And Its Application In DeXing Porphyry Copper Deposit

This paper was supported by the great geological survey projects (No.1212010660604) of China Geological Survey . In this paper, the Near-infrared mineral spectrum analyzer which was jointly developed by Nanjing Institute of Geology and Mineral Resources and Nanjing Zhong Di Instrument Company was taken as testing tool, and the researches about the testing and analysis of Mineral spectrum characteristics, the analysis of mineral spectrum changeability, the establishment of mineral spectrum database, and the application in DeXing porphyry copper deposit were carried out. The key contents of these researches are: analysing the spectrum characteristics of muscovite, montmorillonite, kaolinite, chlorite and other altered minerals and Al-OH, Mg-OH, -OH and other molecule group; studying the influences resulted from mineral mixture, component, structure and granularity to spectrum, starting with mix spectrum, isomorphism and polymorphism; building a small spectrum database and being contrasted to foreign spectrum database; testing the drill cores and section samples in field, and discussing the relation between the spectral reflectivity, intensity and position of Al-OH band and Fe-OH band, Al-OH/OH and mineralization. The resultes are followed:1. The spectrum characteristics are different from mineral to mineral. The spectral band of Al-OH lay around 2200nm, which is single and strong; In 2300nm, Mg-OH's spectral band is single or double strong bands; Corbonate mineral has single strong spectral band in 2350nm; the–OH bands which are in 1400nm and 1900nm can indicate the occurrence status of water in minerals.2. Granularity just influence the spectral reflectivity, mineral spectrum characteristics are determined by component and structure, mineral mixture make the mixspectrum complex.3. The small spectrum database is consistent with foreign sepctrum database in mineral recognition.4. Sericite alteration is widespread in the ore district, the original alteration zone is destroyed seriously by the later period alteration, therefore it is quite difficult to estimate the mineralize position from the altered mineral, but there are tinily differences in the structure and component between the mineralization sericites and the non-mineralization seritcites: The crystallinity of mineralization seritcites is relatively slightly low, but the water content is slightly higher than the non-mineralization seritcites.