Mindat Logo

Cryptomelane

This page is currently not sponsored. Click here to sponsor this page.



Formula:
K(Mn
4+
7
Mn
3+
 
)O
 
16
System:MonoclinicColour:Brown, greyish-white
Lustre:EarthyHardness:5 - 6½
Member of:Coronadite Group > Hollandite Supergroup
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.
This page provides mineralogical data about Cryptomelane.

Classification of Cryptomelane

IMA status:Approved 1982
Strunz 8th edition ID:4/D.08-20
Nickel-Strunz 10th (pending) edition ID: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
Dana 8th edition ID:7.9.1.2

7 : MULTIPLE OXIDES
9 : AB8X16
Hey's CIM Ref.:7.2.4

7 : Oxides and Hydroxides
2 : Oxides of the alkali metals
mindat.org URL:http://www.mindat.org/min-1164.html
Please feel free to link to this page.

Type Occurrence of Cryptomelane

Type Locality:Tombstone, Tombstone District, Tombstone Hills, Cochise Co., Arizona, USA

Physical Properties of Cryptomelane

Lustre:Earthy
Colour:Brown, greyish-white
Streak:Brownish black
Hardness (Mohs):5 - 6½

Crystallography of Cryptomelane

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

Radiation - Copper Kα
Data Set:
Horizontal Axis: ° to ° Vertical Axis: % Source Data: Filtered Data:
Data courtesy of RRUFF project at University of Arizona, used with permission.
X-Ray Powder Diffraction:
d-spacingIntensity
2.39 (100)
6.90 (90)
4.90 (80)
3.10 (80)
2.15 (60)
1.83 (60)
1.54 (60)
Comments:Very similar to coronadite.

Chemical Properties of Cryptomelane

Formula:
K(Mn
4+
7
Mn
3+
 
)O
 
16
Simplified for copy/paste:K(Mn4+7Mn3+)O16
Essential elements:K, Mn, O
All elements listed in formula:K, Mn, O

Relationship of Cryptomelane to other Species

Member of:Coronadite Group > Hollandite Supergroup
Other Members of Group:

- +
Coronadite
Pb(Mn
4+
6
Mn
3+
2
)O
 
16
Ferrihollandite
Ba(Mn
4+
6
Fe
3+
2
)O
 
16
Hollandite
Ba(Mn
4+
6
Mn
3+
2
)O
 
16
Manjiroite
Na(Mn
4+
7
Mn
3+
 
)O
 
16
Strontiomelane
Sr(Mn
4+
6
Mn
3+
2
)O
 
16
Related Minerals - Nickel-Strunz Grouping):

- +
4.DK.05Akaganeite
β-Fe
3+
 
O(OH,Cl)
4.DK.05aCoronadite
Pb(Mn
4+
6
Mn
3+
2
)O
 
16
4.DK.05aHollandite
Ba(Mn
4+
6
Mn
3+
2
)O
 
16
4.DK.05aManjiroite
Na(Mn
4+
7
Mn
3+
 
)O
 
16
4.DK.05bMannardite
Ba(Ti
4+
6
V
3+
2
)O
 
16
4.DK.05bPriderite
K(Ti
4+
7
Fe
3+
 
)O
 
16
4.DK.05bRedledgeite
Ba(Ti
4+
6
Cr
3+
2
)O
 
16
4.DK.05bHenrymeyerite
Ba(Ti
4+
7
Fe
2+
 
)O
 
16
4.DK.05aStrontiomelane
Sr(Mn
4+
6
Mn
3+
2
)O
 
16
4.DK.10Romanèchite
(Ba,H
 
2
O)
 
2
Mn
 
5
O
 
10
4.DK.10Todorokite
(Ca,K,Na,Mg,Ba,Mn)(Mn,Mg,Al)
 
6
O
 
12
· 3H
 
2
O
Related Minerals - Hey's Index Grouping:

- +
7.2.1Lithiophorite
(Al,Li)MnO
 
2
(OH)
 
2
7.2.2Diaoyudaoite
NaAl
 
11
O
 
17
7.2.3Manjiroite
Na(Mn
4+
7
Mn
3+
 
)O
 
16

Other Names for Cryptomelane

Synonyms:
EbelmeniteIMA1982-s.p.
Other Languages:
German:Barium-Kalium-Psilomelan
Ebelmenit
Kryptomelan
Italian:Criptomelano
Russian:Криптомелан
Simplified Chinese:隐钾锰矿
钾硬锰矿
锰钾矿
Spanish:Ebelmenita
Varieties:
Thallian Cryptomelane

Other Information

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

References for Cryptomelane

Reference List:

- +
Richmond, W.E. & M. Fleischer (1942), Cryptomelane, a new name for the commonest of the 'psilomelane' minerals, American Mineralogist: 27: 607-610.

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 Cryptomelane

Search Engines:
  • Look for Cryptomelane on Google
  • Look for Cryptomelane images on Google
  • External Links:
  • Look for Cryptomelane on Webmineral
  • Look for Cryptomelane on Athena Mineralogy
  • Look for Cryptomelane on Wikipedia
  • Look for Cryptomelane on Mineralien Atlas
  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Cryptomelane details from Handbook of Mineralogy (PDF)
  • Mineral Dealers:
  • Buy RARE Minerals from Rocks of Africa
  • Buy minerals from YourMineralCollection
  • Find Cryptomelane on www.crystalclassics.co.uk
  • Buy from McDougall Minerals
  • Buy rare minerals from Excalibur Minerals
  • Buy from David K Joyce minerals
  • Cryptomelane specimens for sale - minfind.com
  • Fine and rare minerals from mintreasure.com
  • DAKOTA MATRIX offers Cabinet and Rare Species from Worldwide Localities.
  • Wilensky Fine Minerals
  • Rare and Unusual minerals at Mineralogical Research Company
  • rare and unusual minerals mainly crystallized
  • Localities for Cryptomelane

    The 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.
    Mineral and/or Locality  
    Search Google  
    Copyright © Jolyon Ralph and Ida Chau 1993-2014. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them. Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of thousands of members and supporters. Mindat does not offer minerals for sale. If you would like to add information to improve the quality of our database, then click here to register.
    Current server date and time: November 3, 2014 06:24:15
    Mineral and Locality Search
    Mineral:
    and/or Locality:
    Options
    Fade toolbar when not in focusFix toolbar to bottom of page
    Hide Social Media Links
    Slideshow frame delay seconds