Pyrophyllite mapping in the Nohwa deposit, Korea, using ASTER remote sensing data

Advanced Spaceborne Thermal Emission and Reflectance Radiometer (ASTER) data were analyzed for the Nohwa deposit area, Korea. The data were calibrated to reflectance using crosstalk correction and atmospheric correction and then used to map pyrophyllite distribution in surface by using band math, combination of Spectral Angle Mapper (SAM), and Matched Filtering (MF) technique. Results from two methods show generally close agreement with the existing alteration map. However, some pixels extracted by band math were vegetation areas not associated with pyrophyllite. In contrast, combination of SAM and MF could detect more accurately areas associated with pyrophyllite than band math. Furthermore, the regional distribution of high-grade and low-grade pyrophyllite in the Nohwa deposit area could be differentiated by combination of SAM and MF. Classification map, according to pyrophyllite grade, using ASTER data is likely to provide ancillary information in development of open-pit mine.