Sturmanite

Sturmanite was first identified in 1983 and approved by the IMA in the same year. It was first found in the Black Rock Mine, Black Rock, Kalahari manganese field, Northern Cape Province, South Africa. It is found as flattened dipyramidal crystals on hematite and baryte. Sturmanite has also been identified in mines near the Black Rock Mine, such as the Wessel's and Perth mines, in the N'Chwaning mines, and near Lakargi Mountain in Russia. It is found as a rare secondary mineral embedded in manganese deposits and is associated with baryte, manganite, hausmannite, and hematite.

The crystal structure of sturmanite shows two distinct features: one being columns of iron-octahedra and calcium polyhedra, the other being the SO4 and B(OH)4 tetrahedra surrounding these columns. These two structures are linked together through a dense and complex network of hydrogen bonds.