Akhtenskite
General
CategoryOxide mineral
Formula
(repeating unit)
MnO2
IMA symbolAkh[1]
Strunz classification4.DB.15b
Crystal systemHexagonal
Dihexagonal dipyramidal class
Space groupHexagonal
H-M symbol: (6/m 2/m 2/m)
Space group: P63/mmc
Unit cella = 2.84, c = 4.6 [Å]; Z = 1
Identification
ColorLight gray to black
Crystal habitFlaky polycrystalline aggregates
CleavageDistinct on {001}
StreakBlack
DiaphaneityOpaque
Specific gravity4.78 (calculated)
Optical propertiesUniaxial
References[2][3][4]

Akhtenskite is a manganese oxide mineral with the chemical formula of MnO2 (or: ε-Mn4+O2[4]) that was named after the Akhtensk deposit in Russia, where it was first discovered and noted in 1979.[3] It can be found in the Akhtensk brown ironstone deposit, in the southern Ural Mountains, on Mt. Zarod, on the Sikhote-Alin Mountains, and in the Primorskiy Krai, all in Russia.[2]

Its crystals are usually hexagonal in shape, with flakiness and plating, usually because it replaced a mineral.[2] Akhtenskite is a polymorphous with the much more widespread pyrolusite. It occurs in mixtures with "psilomelane" (recently renamed to romanechite) and with other manganese oxides in an iron oxide deposit, most likely bacterially altered from a previous mineral in the Akhtensk deposit. It also occurs in crusts of ferromanganese minerals on oceanic rocks.[3] Its chemical makeup is 63% oxygen and 37% manganese.

Some minerals that are commonly associated with akhtenskite are: todorokite, pyrolusite, nsutite, goethite, and cryptomelane.[4]

References

  1. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. 1 2 3 "Fact sheet about Akhtenskite" (PDF). Mineral Data Publishing. Retrieved 2008-05-04.
  3. 1 2 3 "Akhtenskite data sheet". Webmineral.com. Retrieved 2008-05-04.
  4. 1 2 3 Jolyon & Ida Ralph. "Akhtenskite mineral information and data". Mindat.org.


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