Die Feldspatgehalte quartärzeitlicher Sande Niedersachsens

The feldspar contents of 373 samples from quaternary sands of Lower Saxony (West Germany) were determined. The samples were taken in all parts of Lower Saxony and represent a selec- tion of quaternary Sediments of different age and genetic origin. 7 different methods of investigation were tested to determine the content of feldspar both qualitative and quantitative. Polarizing mioroscopy, x-ray diffractometry, Chemical analysis and staining fit these aims best. The most important results of these investigations are: - The quarternary Lower Saxonian sands have an average content of 4.4 weight-% potassium feldspars and 0.8 weight-% plagio- clase. - All tested samples have a similar qualitative feldspar compo- sition. There are monocline, tricline and - more rare - per- thitic potassium feldspars with a rather high (greater 80 %) KAlSi3O8 content. From the plagioclase feldspars only albite, oligoclase and little andesine were indicated. - The potassium feldspar content is higher in each sample than the plagioclase content. - The feldspar content depends on age and genetic origin of each sand. Generally spoken the feldspar content lessens with increasing age. Glaciofluviatile and basin sands usually have a higher feldspar content than fluvial or aeolian sands of the same age. - The feldspar content is highly influenced by grain size com- position. A minimum of feldspar content lies between 0.4 and 1 .0 mm grain size. Fine sands usually have a higher feldspar content than coarse sands. The reason for this phenomenon is weathering. - There are no regional differences in the amount of feldspar content. - The feldspar content is not high enough for commercial mining.