Separate examinations on core and shell of urinary calculi.

Separate core and shell examinations were made on 10,000 urinary stones using a combined crystal-optical X-ray diffractometric method of analysis. 29.5% of these concrements showed differences in qualitative phases between central and peripheral stone parts. All the more frequent stone components were found in core and shell to the same extent. Only weddellite and uric acid dihydrate show a clear preference of the shell. Our method of analysis showed cores to be mostly monomineralic and peripheral stone parts mostly bimineralic. Consequences of this topographic stone analysis for metaphylaxis of urolithiasis are pointed out.