It is undoubtedly true that the development of a country depends on the exploitation of these resources. In the case of Madagascar’s Island, it is home to countless natural biological and mineral resources. Yet the island is underexplored, with most of the country's geological data dating from the 1950s. The use of modern technologies in mineral exploration and research facilitates and gives us many advantages. The time and investment cost will be less, but the results are reliable depending on the procedures to be followed in the processing, analysis and interpretation of the data acquired. By using ENVI software for ASTER and Landsat8 images, Index calculation of certain minerals, color composite and band ratio of the different spectral bands are the methods adopted to see the spatial distribution of gold deposits available in the study area located in the Betsiriry region in the western part of Madagascar. Field survey for verification is always recommended after software treatment, data analyses and interpretation.

Keywords: GIS, Remote Sensing, Gold, Betsiriry , index calculation