1) Dune of sand 
2) Brushwoods on sandy dunes <10% herbs environ) 
3) Clayey soil with 60% short herbs 
4) Gravelled and stony soils with 30% brushwoods 
5) Crust with fragmented stones 
6) Stony structure (Slope of the mountain) 
figure 4 
The methodology, developped at the Geochemistry and metallogeny laboratory 
of the university of PARIS VI, is based on: 
- Diffractometric analysis of samples taken on the ground representative 
of the sandy cover. 
these samples have been divided into two parts: 
- Fine fraction ( sample F). 
- Rough fraction (sample G). 
Each fraction is finely pulverized to obtain a very thin powder in order to 
carry out a diffractometric analysis. This analysis results interpretation is 
given by the figure 5. 
If the spectral signatures curves (figure 6) at samples level do not 
allow us, as in the previous case, to recognize the themes identified on the 
ground (figure 4), as to the dif fractometric analysis it gave us results 
which allow to stand out essentially the minéralogie duality Quartz-Calcite at 
thin fractions level. At the same time, other constituents have been 
identified at rough fractions level, with the help of abacuses , such as 
dolomite, illites, micas as well as clays in little quantity in the test site 
(figure 7). These results wich allow us to identify this variety of soils with 
a good correlation with the ground.