In the amazonian basin, the tropical humid forest covers the majority of the territory and has few infrastructure of access. In the context, many activities are made without being perceived by the coastal population. Thus, some of these activities are practiced totally out law. It is the case for the illegal gold mining which damages the environment and leads to a strong pollution of the rivers, with the use of bad technics and the eagerness caracteristic of the illegal exploitations. At the moment, the increase of the outlaw exploitations and the conflicts it generates with oficial exploitation's owners requires operational means of surveillance. In this article, it is proposed a tecnic based on satellital imagery with the creation of a detection filter. Strong and reliable, it remains with the problem of the clouds, important in tropical regions. Nervertheless, the possibility of obtaining regular informations could become a substancial oportunity for the management of the territory in French Guiana as in the others countries which encounter the same problem with gold mining.