Het voorkomen en de betekenis van kali-houdende mineralen in Nederlandse gronden

The importance of mineralogy and of research on mineral reserves for agriculture and forestry were examined from published data.
Van Baren studied some problems of the mineral associations distinguished by Edelman as petrological provinces or groups. Studies on the heavy fraction (sp.gr.>2.9) of the minerals caused him to introduce new divisions of the B Elsloo province and to introduce a new province, the B Eysden province. The light fraction (sp.gr. < 2.9) could also be classified into provinces. Thus it was possible to obtain a picture of the distribution of feldspars in Dutch sands. Lastly he studied the fraction < 30μ . Three Dutch clays completely different in K content were examined microscopically and radiographically for mineralogical causes of the difference; results were unexpectedly good. In clays also was there a provincial character, according to origin. Mixture of two sediments in the finer fractions proved sometimes to be completely different from that of the coarser fractions. There was a parallel between natural fertility and mineralogical composition.