Jimboite exhibited at the Mining Museum of Akita University — Photo: 掬茶 · CC BY-SA 4.0
Jimboite
Jimboite is an IMA-recognized mineral species in the borate class, with the chemical formula Mn²⁺₃(BO₃)₂.
It crystallizes in the orthorhombic crystal system (space group Pnmn).
Key properties: Mohs hardness 5.5; specific gravity 3.98–4.02; Vitreous luster; optically biaxial.
IMA symbol Jbo, IMA status: approved, named in 1963.
Likely formed by metasomatic reactions between boron-bearing hydrothermal solutions and rhodochrosite in banded manganese deposits.
It is found associated with Rhodochrosite, tephroite, galaxite, jacobsite, alabandite, galena, pyrrhotite, chalcopyrite.
The mineral was named to honor Professor Kotora Jimbo (1867–1924), founder of the Mineralogical Institute, University of Tokyo, Tokyo, Japan.