Akhtenskite is a rare manganese oxide mineral that typically occurs as thin, black hexagonal plates or earthy aggregates within manganese-rich deposits. It is structurally very similar to pyrolusite and is often identified through X-ray diffraction due to its subtle structural differences. Collectors look for these specimens primarily in localities where secondary manganese minerals are formed by weathering.
Is this akhtenskite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch akhtenskite with a known reference. Akhtenskite sits at Mohs 2-3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: black, gray.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: massive, aggregates of thin hexagonal plates.
Often confused with
Akhtenskite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Nsutite is the harder of the two (Mohs 6.5-8.5 vs. 2-3).
How to tell apart: Streak differs, so Akhtenskite leaves black, Birnessite leaves brownish-black; luster reads metallic on Akhtenskite and dull on Birnessite.
Often found alongside akhtenskite
Minerals reported to co-occur with akhtenskite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- MnO₂
- Mohs hardness
- 2-3
- Density
- 4.78 g/cm³
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Hexagonal
- Crystal habit
- Massive, aggregates of thin hexagonal plates
- Cleavage
- {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In mixtures in “psilomelane” with other manganese oxides in an iron oxide deposit, probably bacterially altered from a previous mineral (Akhtensk deposit, Russia)
Where rockhounds find akhtenskite
Classic worldwide localities
- Akhtensk brown ironstone deposit, north of Magnitka, Southern Ural Mountains, Russia
- Mt. Zarod, Sikhote-Alin Mountains, Primorskiy Kray, Russia
Field-hunting tip
Where it forms: In mixtures in “psilomelane” with other manganese oxides in an iron oxide deposit, probably bacterially altered from a previous mineral (Akhtensk deposit, Russia). If you start seeing cryptomelane, nsutite, pyrolusite in float, you are in the right ground. Typical habit: massive, aggregates of thin hexagonal plates. Train your eye for that shape before scanning the outcrop.
Common questions
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Find akhtenskite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
