The sum of the Qs (Q1 + Q2) for the two Verhulst functions is 49322 metric tonnes. The amount extracted by 2005 was 11010 metric tonnes. The reserves plus the amount extracted is 82020 metric tonnes and the reserves base plus the amount extracted is 91020 metric tonnes. So the sum of the Qs is slightly less than half the reserves base plus the amount extracted.

The 1980 peak for World platinum- group was probably due to the fact that the United States extraction had declined after a small peak. It appears that the World platinum group has a decade or more to go before peaking and there may be more peaks in the future.