Nambulite exhibited at the Mining Museum of Akita University — Photo: 掬茶 · CC BY-SA 4.0
Nambulite
A lithium-bearing manganese silicate named for Tohoku University manganese specialist Matsuo Nambu.
Intro adapted from Wikipedia (CC BY-SA).
Nambulite is an IMA-recognized mineral species in the silicate class, with the chemical formula LiMn²⁺₄Si₅O₁₄(OH).
It crystallizes in the triclinic crystal system (space group P-1). It is a member of the Rhodonite structural group.
Key properties: Mohs hardness 6.5; specific gravity 3.53; Pale yellow streak; Vitreous luster; refractive index 1.716; optically biaxial.
IMA symbol Nbl, IMA status: approved, named in 1971.
Found in veinlets cutting braunite ores in chert (Funakozawa mine, Japan).
It is found associated with Braunite, albite, neotocite, rhodochrosite (Funakozawa mine, Japan).
The name refers to Professor Matsuo Nambu, Tohoku University, Sendai, Japan.