D. Kamińska, S. Kamiński, KAMIKA Instruments, Warszawa, Poland

 In commonly adopted opto-electronic measuring methods each measured grain is compared to a sphere, independently of its actual shape, only having in mind the calculation simplicity. With such a method the grain-size characteristics of the given material is explicitly defined. In case when such results are compared with the mechanical sieving results, it is possible to make conclusions about the grain form, because the measurement of spherical particles should give similar results in both methods, while the larger are the differences in measurements, then the particles are more elongated or flattened.