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Cryptomelane

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Formula:
K(Mn4+7Mn3+)O16
Colour:
Brown, grayish-white
Lustre:
Resinous, Dull, Earthy
Hardness:
5 - 6½
Specific Gravity:
4.17 - 4.41
Crystal System:
Monoclinic
Name:
Named in 1942 by Wallace E. Richmond and Forrest A. Gonyer From the Greek words meaning κρυπτοζ "hidden" and ρελαζ "black," since as the identity of this common black manganese mineral has been hidden within a group of manganese oxides.
Many manganese oxides are better identified using infra-red spectroscopy than by x-ray diffraction because of issues of crystal size, disorder, etc. (Potter and Rossman, 1979).


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Classification of CryptomelaneHide

Approved, 'Grandfathered' (first described prior to 1959)
Approval Year:
1982
4.DK.05a

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar
K : With large (+- medium-sized) cations; tunnel structures
7.9.1.2

7 : MULTIPLE OXIDES
9 : AB8X16
7.2.4

7 : Oxides and Hydroxides
2 : Oxides of the alkali metals

Physical Properties of CryptomelaneHide

Resinous, Dull, Earthy
Transparency:
Opaque
Colour:
Brown, grayish-white
Streak:
Brownish black
Hardness:
5 - 6½ on Mohs scale
Tenacity:
Brittle
Density:
4.17 - 4.41 g/cm3 (Measured)    4.44 g/cm3 (Calculated)

Chemical Properties of CryptomelaneHide

Formula:
K(Mn4+7Mn3+)O16

Age informationHide

Age range:
Lopingian : 253 ± 5 Ma to 253 ± 5 Ma - based on data given below.
Sample ages:
Sample IDRecorded ageGeologic TimeDating method
1253 ± 5 MaLopingianK-Ar
Sample references:
IDLocalityReference
1Eisenbach, Titisee-Neustadt, Black Forest, Baden-Württemberg, GermanyPfaff, K., Romer, R. L., & Markl, G. (2009) U-Pb ages of ferberite, chalcedony, agate,‘U-mica’and pitchblende: constraints on the mineralization history of the Schwarzwald ore district. European Journal of Mineralogy, 21(4), 817-836.

Crystallography of CryptomelaneHide

Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Cell Parameters:
a = 9.956 Å, b = 2.8705 Å, c = 9.706 Å
β = 90.95°
Ratio:
a:b:c = 3.468 : 1 : 3.381
Unit Cell V:
277.35 ų (Calculated from Unit Cell)
Z:
1
Comment:
Non-standard I2/m setting; pseudo-tetragonal

X-Ray Powder DiffractionHide

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Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.
Powder Diffraction Data:
d-spacingIntensity
6.90 (90)
4.90 (80)
3.45 (10)
3.10 (80)
2.46 (10)
2.39 (100)
2.19 (20)
2.15 (60)
1.92 (10)
1.83 (60)
1.64 (30)
1.54 (60)
1.42 (40)
1.35 (50)
1.29 (20)
Comments:
ICDD 20-908 (Tetragonal; Phillipsburg, Montana, USA). Very similar to coronadite. ICDD 34-168 (Monoclinic; Chindwara, India; calculated): 7.007 (79), 6.892 (82), 4.977 (72), 4.852 (91), 3.504 (15), 3.446 (15), 3.156 (43), 3.124 (99), 3.092 (100), 3.062 (44), 2.753 (3), 2.489 (25), 2.426 (22), 2.414 (54), 2.404 (99), 2.393 (77), 2.336 (10), 2.297 (6), 2.229 (5), 2.195 (20), 2.171 (36), 2.147 (33), 1.9897 (5), 1.9636 (4), 1.9567 (7), 1.9440 (3), 1.9110 (5), 1.8991 (2), 1.8504 (24), 1.8417 (22), 1.8258 (19), 1.8175 (32), 1.7518 (3), 1.7230 (3), 1.6876 (3), 1.6831 (3),1.6591 (24), 1.6360 (3), 1.6266 (3), 1.6174 (25), 1.6092 (15), 1.6079 (4), 1.5779 (3), 1.5567 (14), 1.5439 (32), 1.5362 (28), 1.5308 (17), 1.5239 (15), 1.4353 (19), 1.4239 (5)

Type Occurrence of CryptomelaneHide

Synonyms of CryptomelaneHide

Other Language Names for CryptomelaneHide

Varieties of CryptomelaneHide

Thallian CryptomelaneA thallium-bearing Cryptomelane (0.23 at% Tl).
Originally reported from Peach Springs District, Coconino Co., Arizona, USA.

Relationship of Cryptomelane to other SpeciesHide

Other Members of this group:
CoronaditePb(Mn4+6Mn3+2)O16Mon. 2/m
FerricoronaditePb(Mn4+6Fe3+2)O16Tet. 4/m : I4/m
FerrihollanditeBa(Mn4+6Fe3+2)O16Mon. 2/m
HollanditeBa(Mn4+6Mn3+2)O16Mon. 2/m
ManjiroiteNa(Mn4+7Mn3+)O16Tet. 4/m : I4/m
StrontiomelaneSr(Mn4+6Mn3+2)O16Mon. 2/m : P21/b

Common AssociatesHide

Associated Minerals Based on Photo Data:
Scholzite7 photos of Cryptomelane associated with Scholzite on mindat.org.
Hematite7 photos of Cryptomelane associated with Hematite on mindat.org.
Goethite6 photos of Cryptomelane associated with Goethite on mindat.org.
Pyrolusite5 photos of Cryptomelane associated with Pyrolusite on mindat.org.
Adamite5 photos of Cryptomelane associated with Adamite on mindat.org.
Fluorapatite4 photos of Cryptomelane associated with Fluorapatite on mindat.org.
Lotharmeyerite4 photos of Cryptomelane associated with Lotharmeyerite on mindat.org.
Epididymite4 photos of Cryptomelane associated with Epididymite on mindat.org.
Beryllite4 photos of Cryptomelane associated with Beryllite on mindat.org.
Hollandite4 photos of Cryptomelane associated with Hollandite on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

4.DK.05Akaganeite(Fe3+,Ni2+)8(OH,O)16Cl1.25 · nH2OMon. 2/m
4.DK.05aCoronaditePb(Mn4+6Mn3+2)O16Mon. 2/m
4.DK.05aHollanditeBa(Mn4+6Mn3+2)O16Mon. 2/m
4.DK.05aManjiroiteNa(Mn4+7Mn3+)O16Tet. 4/m : I4/m
4.DK.05bMannarditeBa(Ti4+6V3+2)O16Tet. 4/m : I41/a
4.DK.05bPrideriteK(Ti4+7Fe3+)O16Tet.
4.DK.05bRedledgeiteBa(Ti4+6Cr3+2)O16Tet.
4.DK.05bHenrymeyeriteBa(Ti4+7Fe2+)O16Tet. 4/m : I4/m
4.DK.05aStrontiomelaneSr(Mn4+6Mn3+2)O16Mon. 2/m : P21/b
4.DK.10Romanèchite(Ba,H2O)2(Mn4+,Mn3+)5O10Mon. 2/m
4.DK.10Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2OMon. 2/m : P2/m

Related Minerals - Dana Grouping (8th Ed.)Hide

7.9.1.1HollanditeBa(Mn4+6Mn3+2)O16Mon. 2/m
7.9.1.3ManjiroiteNa(Mn4+7Mn3+)O16Tet. 4/m : I4/m
7.9.1.4CoronaditePb(Mn4+6Mn3+2)O16Mon. 2/m

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

7.2.1Lithiophorite(Al,Li)MnO2(OH)2Trig. 3m (3 2/m) : R3m
7.2.2DiaoyudaoiteNaAl11O17Hex.
7.2.3ManjiroiteNa(Mn4+7Mn3+)O16Tet. 4/m : I4/m

Fluorescence of CryptomelaneHide

Not fluorescent in ultraviolet

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for CryptomelaneHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Richmond, W. E. and Michael Fleischer (1942): Cryptomelane, a new name for the commonest of the 'psilomelane' minerals. American Mineralogist: 27: 607-610.
Larson, L. T. (1964): Geology and Mineralogy of Certain Manganese Oxide Deposits, Economic Geology, 59, 54-78.
Potter, Russell M. and Rossman, George R. (1979): The tetravalent manganese oxides: identification, hydration, and structural relationships by infrared spectroscopy. American Mineralogist, 64, 1199-1218.
Post, J. E., Von Dreele, R. B., and Buseck, P. R. (1982): Symmetry and cation displacements in hollandites: structure refinements of hollandite, cryptomelane and priderite. Acta Crystallogr.: B38: 1056-1065.

Internet Links for CryptomelaneHide

Localities for CryptomelaneHide

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListShow

Mineral and/or Locality  
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