Johannes Otto Conrad Mügge (4 March 1858, Hannover – 9 June 1932, Göttingen) was a German mineralogist and crystallographer.
After graduation, he spent three years as an assistant to Harry Rosenbusch at the mineralogical-geological institute of the University of Heidelberg.
From 1882 he worked as curator of the mineralogical and geological department at the Natural History Museum in Hamburg, and in 1886 became an associate professor at the academy in Münster.
[2] He was the author of 152 scientific works; dealing with subjects such as, the translation of crystals by mechanical deformation, the regular adhesion of different types of minerals, the formation temperature of quartz and plagioclase twinning, the correlation of pleochroic haloes with radioactive radiation and the petrography of selected rock complexes in Westphalia, Hesse and the Harz.
[1][3] With Ernst Anton Wülfing, he published the fifth edition of Harry Rosenbusch's Mikroskopische Physiographie der Mineralien und Gesteine (1921–27).