Help mindat.org|Log In|Register|
Home PageMindat NewsThe Mindat ManualHistory of MindatCopyright StatusManagement TeamContact UsAdvertise on Mindat
Donate to MindatSponsor a PageSponsored PagesTop Available PagesMindat AdvertisersAdvertise on MindatThe Mindat Store
Minerals by PropertiesMinerals by ChemistryRandom MineralSearch by minIDLocalities Near MeSearch GlossaryMore Search Options
Search For:
Mineral Name:
Locality Name:
Keyword(s):
 
The Mindat ManualAdd a New PhotoRate PhotosLocality Edit ReportCoordinate Completion ReportAdd Glossary Item
StatisticsThe ElementsMember ListBooks & MagazinesMineral Shows & EventsThe Mindat DirectoryHow to Link to MindatDevice Settings
Photo SearchPhoto GalleriesNew Photos TodayNew Photos YesterdayMembers' Photo GalleriesPast Photo of the Day Gallery

Cryptomelane

This page is currently not sponsored. Click here to sponsor this page.
Formula:
K(Mn74+Mn3+)O16
System:
Monoclinic
Colour:
Brown, grayish-white
Lustre:
Resinous, Dull, Earthy
Hardness:
5 - 6½
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).

Classification of Cryptomelane

Approved 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
mindat.org URL:
http://www.mindat.org/min-1164.html
Please feel free to link to this page.

Type Occurrence of Cryptomelane

Physical Properties of Cryptomelane

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

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:
Data courtesy of RRUFF project at University of Arizona, used with permission.
X-Ray 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)

Chemical Properties of Cryptomelane

Formula:
K(Mn74+Mn3+)O16
All elements listed in formula:

Relationship of Cryptomelane to other Species

Other Members of Group:
CoronaditePb(Mn64+Mn23+)O16
FerrihollanditeBa(Mn64+Fe23+)O16
HollanditeBa(Mn64+Mn23+)O16
ManjiroiteNa(Mn74+Mn3+)O16
StrontiomelaneSr(Mn64+Mn23+)O16
4.DK.05Akaganeiteβ-Fe3+O(OH,Cl)
4.DK.05aCoronaditePb(Mn64+Mn23+)O16
4.DK.05aHollanditeBa(Mn64+Mn23+)O16
4.DK.05aManjiroiteNa(Mn74+Mn3+)O16
4.DK.05bMannarditeBa(Ti64+V23+)O16
4.DK.05bPrideriteK(Ti74+Fe3+)O16
4.DK.05bRedledgeiteBa(Ti64+Cr23+)O16
4.DK.05bHenrymeyeriteBa(Ti74+Fe2+)O16
4.DK.05aStrontiomelaneSr(Mn64+Mn23+)O16
4.DK.10Romanèchite(Ba,H2O)2Mn5O10
4.DK.10Todorokite(Ca,K,Na,Mg,Ba,Mn)(Mn,Mg,Al)6O12 · 3H2O
7.2.1Lithiophorite(Al,Li)MnO2(OH)2
7.2.2DiaoyudaoiteNaAl11O17
7.2.3ManjiroiteNa(Mn74+Mn3+)O16

Other Names for Cryptomelane

Other Information

Not fluorescent in ultraviolet
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 Cryptomelane

Reference List:
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, v. 59, p. 54-78.
Potter, Russell M. and Rossman, George R. (1979) The tetravalent manganese oxides: identification, hydration, and structural relationships by infrared spectroscopy, American Mineralogist, v. 64, p. 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 Cryptomelane

Specimens:
The following Cryptomelane specimens are currently listed for sale on minfind.com.

Localities for Cryptomelane

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  
Mindat.org is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2016, except where stated. Mindat.org relies on the contributions of thousands of members and supporters.
Privacy Policy - Terms & Conditions - Contact Us Current server date and time: February 9, 2016 13:56:42 Page generated: February 4, 2016 17:30:31