Long prismatic semimetallic crystals of the very rare Mn mineral akhtenskite from the type locality in Akhtenskoe Fe deposit, Russia (Akhtenskoe, Magnitka, Kusinskii Raion, Chelyabinsk Oblast, Russian Federation) and only one of the very few known localities worldwide. Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY 4.0
Akhtenskite
A manganese dioxide polymorph named for the Akhtensk deposit in Russia, where it was recognized in 1979.
Intro adapted from Wikipedia (CC BY-SA).
Akhtenskite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula MnO₂.
It crystallizes in the hexagonal crystal system (space group P6_3mc). It is a member of the Feroxyhyte structural group.
Key properties: specific gravity 4.78; optically uniaxial.
IMA symbol Akh, IMA status: approved, named in 1982.
Found in mixtures in “psilomelane” with other manganese oxides in an iron oxide deposit, probably bacterially altered from a previous mineral (Akhtensk deposit, Russia).
It is found associated with Cryptomelane, nsutite, pyrolusite, todorokite, goethite (Akhtensk deposit, Russia); vernadite, manganite, Fe–Mn oxides (Mt. Zarod, Russia).
The name refers to the Akhtensk deposit, Russia, where it was first noted.