Yellow crystal aggregates of the extremely rare Mn mineral bunnoite (IMA2014-054) from the type and only known locality worldwide in Japan (Kamoyama Mine, Ino, Agawa District, Shikoku Island, Japan). Ex. Erich Laskowski collection (USA). — Photo: David Hospital · CC BY 4.0
Bunnoite
Bunnoite is an IMA-recognized mineral species in the silicate class, with the chemical formula Mn²⁺₆AlSi₆O₁₈(OH)₃.
It crystallizes in the triclinic crystal system (space group P-1).
Key properties: Mohs hardness 5.5; specific gravity 3.63; Dull green streak; Vitreous luster; optically biaxial.
IMA symbol Bno, IMA status: approved, named in 2014.
Found in veinlets cutting metamorphosed iron- and manganese-rich marine sediments.
It is found associated with Stilpnomelane, rhodonite, piemontite, quartz.
The mineral was named to honor the Japanese mineralogist Michiaki Bunno (b. 1942), retired chief curator for the Geological Museum of the Geological Survey of Japan.