Akhtenskite

akhtenskite

vernadite

buserite

nsutite

Images

Formula: MnO₂
Valence: Mn⁴⁺O^2-₂
Simple oxide of manganese Mn⁴⁺, ramsdellite group, hexagonal paramorph of tetragonal pyrolusite and orthorhombic ramsdellite
Crystal system: Hexagonal
Specific gravity: 4.78 calculated
Streak: Black
Colour: Light grey to black
Environments

Volcanic igneous environments

Localities

At the type locality, the Akhtenskoe Fe deposit, Magnitka, Kusinsky District, Chelyabinsk Oblast, Russia, akhtenskite occurs as light grey to black mixtures with cryptomelane and nsutite in a specimen of psilomelane from the limonite deposit. The akhtenskite occurs as platy aggregates (AM 75.931-937).
Other associated minerals include pyrolusite, todorokite and goethite. The akhtenskite occurs as flaky to platy microscopic crystals in parallel aggregates, sometimes in rows at 120◦, probably due to replacement of an earlier hexagonal mineral (HOM).

At Zarod Mt, Primorsky Krai, Russia, akhtenskite has been identified as flaky polycrystalline aggregates in ferromanganese encrustations on oceanic basalt from a guyot (a flat-topped undersea mountain). Associated minerals include vernadite and buserite (AM 75.931-937).

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