Gustav Bernhard Duft, a mining engineer and former member of the German Imperial Mining Board, wrote a brief Report upon the Knysna Goldfields, which was published as a Cape of Good Hope Parliamentary Report in 1889. It dealt with his tour of inspection of the Knysna region, particularly around Millwood, and described its geology and gold finds.
In August 1892 Duft was appointed as head of the Mining Commission of German South West Africa (now Namibia) in Windhoek. He held this position until 1904 and also served as district commissioner of Windhoek at the same time. During this period he published a paper, in German, on the copper deposits of that country in the Sudafrikanische Wochenschrift (1899, pp. 343-346, 676-679, 711-713). The mineral duftite (a secondary copper mineral first found in Namibia) was named after him. In 1903 the Mining Commission was made responsible for geological research in the territory and this led Duft to recruit the geologist Dr F.W. Voit* to undertake such work.
Duft was an early member of the South African Association for the Advancement of Science in 1903, identified in the list of members as "Gustav Duft, Kaiserlicher Bergrath, Windhoek" (i.e., Royal Mining Superintendent of German South West Africa). In 1906 he published, with one Dickens and A. Diefenbach as co-authors, a brief paper (in German) on the copper deposits at Otjizonyati (or Otyosonjati - not identified), in the Deutsches Kolonialblatt. In the same year he contributed a chapter on the present state of mining in German South West Africa to a book edited by the governor of the territory, T.G. Leutwein, Elf jahre Gouverneur in Deutsch-Sudwestafrika (Berlin, 1906; 3d ed. 1908, pp. 375-390).