“…[20,26,33,36,40,42,44,45] 2.1.3 ␣-, -Hausmannite (Mn 3 O 4 ), Pyrolusite (MnO 2 ), and Bixbyite (Mn 2 O 3 ). The question of the homogeneity range of ␣-and -hausmannite has been investigated by a number of authors, some of whom declare haus- [26,29,[46][47][48] while others find differing degrees of nonstoichiometry. [15,16,27,39,41,[49][50][51][52] The most reliable and most recent investigation seems to be the one from Keller and Dieckmann, [53] who determined the maximum homogeneity range of Mn 3−␦ O 4 to be 0.5710 < x O < 0.5717, i.e., very small.…”