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hollandite

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Hollandite (chemical formula: Ba(Mn4+6Mn3+2)O16) is a manganese oxide mineral. Its structure consists of double chains of MnO6 octahedra delimiting 2 × 2 tunnels. The electrostatic charge created by the Mn3+ for Mn4+ substitution is balanced by cations in the tunnels. Their nature determines the mineral species: Ba for hollandite, K for cryptomelane, Pb for coronadite, Sr for strontiomelane, Tl for thalliomelane, and Na for manjiroite. Pure species are rare and most 2 × 2 tectomanganates contain mixtures of several types of tunnel cations.

Key facts

Mineral.name
Hollandite
Mineral.category
Oxide minerals
Mineral.image
File:Hollandite-171530.jpg
Mineral.formula
Ba(Mn4+6Mn3+2)O16
Mineral.IMAsymbol
Hol
Mineral.strunz
4.DK.05a
Mineral.dana
7.9.1.1
Mineral.system
Monoclinic
Mineral.class
Prismatic (2/m)
Mineral.symmetry
Monoclinic H-M symbol: (2/m) Space group: I2/m
Mineral.color
Silvery-grey to greyish
Mineral.cleavage
Distinct / Good, Prismatic
Mineral.mohs
4 to 6
Mineral.density
4.95

via Wikipedia infobox

Wikidata facts

Image
Hollandite-95021.jpg
Show 7 more facts
Commons category
Hollandite
Nickel-Strunz 9th edition (updated 2009)
4.DK.05
Nickel-Strunz '10th ed', review of (9th ed/ 2009 update)
4.DK.05a
IMA Mineral Symbol
Hol
chemical formula
Ba(Mn⁴⁺₆Mn³⁺₂)O₁₆
Strunz 8th edition (series ID, updated)
IV/D.03b
Sources (3)

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Encyclopedic overview

2 sections
Contents
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  • References

Hollandite (chemical formula: Ba(Mn4+6Mn3+2)O16) is a manganese oxide mineral. Its structure consists of double chains of MnO6 octahedra delimiting 2 × 2 tunnels. The electrostatic charge created by the Mn3+ for Mn4+ substitution is balanced by cations in the tunnels. Their nature determines the mineral species: Ba for hollandite, K for cryptomelane, Pb for coronadite, Sr for strontiomelane, Tl for thalliomelane, and Na for manjiroite. Pure species are rare and most 2 × 2 tectomanganates contain mixtures of several types of tunnel cations.

A mineral, with the chemical composition BaMn4+6Fe3+2O16, that was first found in the Kajlidongri mine in the Jhabua district of Madhya Pradesh, India, had the name hollandite until it was reclassified as ferrihollandite by the International Mineralogical Association in 2012. Ferrihollandite is the barium-iron (III) endmember of the coronadite group.

Excerpted from Wikipedia’s “hollandite” article, available under the CC BY-SA 4.0 licence.