| Abstract: | A geochemical soil survey in the vicinity of the known ore body at Lontzen (Belgium) revealed numerous lead and/or zinc anomalies. Three soil traverses were selected in this area and examined for possible contamination. Two anomalous samples from one traverse were obviously contaminated (brick fragments). A sequential selective extraction procedure was applied to the soil samples, using a modification of the method of Gatehouse et al.Using this procedure, lead anomalies related to the probable extension of a known galena-sphalerite vein appear in every dissolution step. In contrast, in contaminated samples, only the final acid digestion produced anomalous values. One may thus suppose that contamination of the sample adds metal in the form of a resistant phase which is only dissolved by strong acid reagents. It should be noted that the contrast between anomalous and background values is highest for hydroxylamine hydrochloride and about the same for all other dissolution steps.The samples were also submitted to non-sequential selective extractions. The calculation of the difference between non-sequential and sequential extractions leads to the localization of two highly contrasted peaks which correspond exactly with the ore veins. |
