:An ugglity for most people, but a jewel for a speciescollector. Collection and photo Erik Vercammen Locality: Yuzhno-Faizulinskoe Mn deposit, Sibay, Bashkortostan Republic, Southern Urals, Urals Region, Russia — Photo: Erik Vercammen · CC BY 3.0
Ribbeite
Ribbeite is an IMA-recognized mineral species in the silicate class, with the chemical formula Mn²⁺₅(SiO₄)₂(OH)₂.
It crystallizes in the orthorhombic crystal system (space group Pnma). It is a member of the Humite structural group.
Key properties: Mohs hardness 5; specific gravity 3.9; Light pink streak; Vitreous luster; optically biaxial.
IMA symbol Rib, IMA status: approved, named in 1985.
Found in mineralogically distinct layers, in tectonically transported and boudinaged manganese-rich lenses within dolostones, apparently formed under prograde metamorphic conditions.
It is found associated with Alleghanyite, manganoan calcite, pyrochroite, chlorite, galaxite, jacobsite.
The mineral was named to honor Dr. Paul H. Ribbe, Virginia Polytechnic Institute, Blacksburg, Virginia, USA.