Ullmannite is steel-gray to tin white in color with a metallic luster, has a Mohs hardness of 5 to 5.5 and a specific gravity of 6.65.

[5] Variance in its chemical composition has been shown to be responsible for loss of symmetry and variations in striation patterns.

It occurs with nickeline, gersdorffite, pentlandite, chalcopyrite, pyrrhotite, galena, tetrahedrite and dyscrasite in hydrothermal deposits.

[8] Ullmannite was named for German chemist and mineralogist, Johann Christoph Ullmann (1771–1821), one of the fathers of systematic mineralogy.

Ullmann established a mineral collection (now the basis for the internationally renowned Museum of Mineralogy in Marburg[9]) and authored Ein Systematisch-Tabellarische Übersicht der Mineralogisch einfachen Fossilien, one of the first attempts to provide a structured organization to the observed minerals of the day.