Grey brownish aggregates of the very rare Mn mineral feitknechtite associated to pinkish rhodonite from Japan (Fujii Mine, Wakasa-cho, Mikatakaminaka District, Fukui Prefecture, Honshu Island, Japan). Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY 4.0
Feitknechtite
Feitknechtite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula Mn³⁺O(OH).
It crystallizes in the hexagonal crystal system (space group P-3m1).
Key properties: specific gravity 3.249; Dull luster.
IMA symbol Fkn, IMA status: approved, named in 1965.
Found in a mixture with hausmannite, formed by supergene oxidation of and replacing earlier pyrochroite.
It is found associated with Pyrochroite, hausmannite.
The mineral was named to honor Dr. Walter Feitknecht (1899–?), Swiss Professor of Chemistry, University of Berne, Berne, Switzerland, who synthesized the compound.