Appointed Special Mint Warden for the Cologne Circle, Germany, on 8 May 1643, immediately following the death of his uncle
Konrad Duisberg. Johann Duisberg left office by 10 May 1644, was on the employee list in 1655 but no longer in 1686. Lit.:
Alfred Noss, Die Münzen der Städte Köln und Neuss: 1474-1794 (1926) pp. 47-49, 185; Wolfgang Scheffler, Goldschmiede Rheinland-Westfalens
- Aachen - Köln (1973) n. 1380, p. 510.