Eingestellte DIW Publikationen 1 / 1971, S. 65-68
Ferdinand Friedensburg
In addition to the gaps and undependability which beset all international statistics, certain specific difficulties also detract much from international mining statistics. Some of these are the application of countless different weights and measures, the differing demarcations between mining production itself and processing of mining products, and in the change frequently not comparable qualities of the extracted minerals. In order to enable any kind of international comparisons at all, it is recommended that the official figures of American mining statistics for 1956 be utilized as a base. There exists particular reason for doubt with regard to the usual figures on geological reserves.