cryptomelane
Sign in to saveAlso known as ebelmenite
Cryptomelane (K(Mn4+,Mn2+)8O16) is the potassium endmember of the hollandite group, a family of tectomanganates with a 2 × 2 tunnel structure.
Key facts
- Mineral.name
- Cryptomelane
- Mineral.image
- Kryptomelan2, Maroko.jpg
- Mineral.imagesize
- 260px
- Mineral.category
- Oxide mineral
- Mineral.formula
- K(Mn4+,Mn2+)8O16
- Mineral.IMAsymbol
- Cml
- Mineral.strunz
- 4.DK.10
- Mineral.system
- Tetragonal
- Mineral.class
- Dipyramidal (4/m) H-M symbol: (4/m)
- Mineral.symmetry
- I4/m
- Mineral.unit cell
- a = 9.956 Å, b = 2.8705 Å, c = 9.706 Å; β = 90.95°; Z = 1
- Mineral.color
- Steel-gray to bluish gray; light tan or gray in reflected light
- Mineral.habit
- Rare as subhedral crystals, commonly as compact fine-grained masses, banded colloform, botryoidal, or radial fibrous aggregates
- Mineral.twinning
- Twinning developed on (010) and (101) resulting in a pseudotetragonal unit cell.
- Mineral.fracture
- Conchoidal
- Mineral.tenacity
- Brittle
- Mineral.mohs
- 6 – 6.5
- Mineral.luster
- Metallic to dull
via Wikipedia infobox
Wikidata facts
- Named after
- secrecy
- Image
- Kryptomelan2, Maroko.jpg
Show 7 more facts
- Nickel-Strunz '10th ed', review of (9th ed/ 2009 update)
- 4.DK.05a
- Nickel-Strunz 9th edition (updated 2009)
- 4.DK.05
- Commons category
- Cryptomelane
- type locality (geology)
- Tombstone
- crystal system
- monoclinic crystal system
- IMA Mineral Symbol
- Cml
- chemical formula
- K(Mn⁴⁺₇Mn³⁺)O₁₆
Sources (2)
via Wikidata · CC0
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Encyclopedic overview
1 sectionsContents
- References
Cryptomelane (K(Mn4+,Mn2+)8O16) is the potassium endmember of the hollandite group, a family of tectomanganates with a 2 × 2 tunnel structure.
In 1942 the name cryptomelane was proposed as part of an effort to sort out the manganese oxide minerals referred to as psilomelane. Cryptomelane was identified and defined based on X-ray diffraction studies of samples from Tombstone, Arizona; Deming, New Mexico; Mena, Arkansas; and Philipsburg, Montana.
Excerpted from Wikipedia’s “cryptomelane” article, available under the CC BY-SA 4.0 licence.