Prospecting is a discipline of geology that deals with the search for new mineral deposits (anomalies), and therefore requires the use of a number of methods of which those who carry them out are sometimes unaware, leading to mediocre results after much effort.Nevertheless, in the field of earth sciences (geology), there are simple methods proposed by scientists that can be made available to communities in order to overcome these obstacles. These include geochemical and geophysical methods, which may be developed further as part of our research.Idjwi is one of the largest islands in the African lakes. It lies in Lake Kivu, in the western branch of the East African Rift system. The petrographic and structural study of this western part of the East African Rift has enabled us to determine certain geological formations and to orientate certain brittle deformations (diaclase, joint) on the basis of tectonic parameters such as the orthogonal principal stress tensor.