Cryptomelane Mineral Data

[Mineral Auctions] [Register] [Current Auctions] [Log In] [www.danweinrich.com]
Dan Weinrich Auctions
Specializing In Live Weekly Auctions Of Top Quality Mineral Specimens
The Place To Find Great Specimens At Great Prices!

General Cryptomelane Information

Chemical Formula:

K(Mn++++,Mn++)8O16

Composition:

Molecular Weight = 734.59 gm

Potassium 5.32 % K 6.41 % K₂O

Manganese 59.83 % Mn 19.31 % MnO / 71.01 % MnO₂

Oxygen 34.85 % O

______ ______

100.00 % 96.73 % = TOTAL OXIDE

Empirical Formula:

KMn⁴⁺₆Mn²⁺₂O₁₆

Environment:

Commonest of the hard, black, fine-grained manganese oxides formerly called psilomelane.

IMA Status:

Valid Species (Pre-IMA) 1942

Locality:

Chindwara, India. Link to MinDat.org Location Data.

Name Origin:

From the Greek for hidden and black, as the identity of this common, black mineral is lost in the group of other black Mn-bearing oxides.

Name Pronunciation:

Cryptomelane + Pronunciation

Synonym:

Psilomelane

Cryptomelane Image

Images:

Click Here for Larger Cryptomelane Image

Cryptomelane Adamite

Comments: Black, rounded balls of cryptomelane and purple, transparent adamite.
Location: Ojuela mine, Mapimi, Druango, Mexico. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Cryptomelane Crystallography

Axial Ratios:

a:b:c =3.3993:1:3.4513

Cell Dimensions:

a = 9.79, b = 2.88, c = 9.94, Z = 1; beta = 90.62° V = 280.24 Den(Calc)= 4.35

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: I2/m

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 2.399(1), 1.654(0.8), 3.11(0.8),

Crystal Structure:

Mouse
drag1 - LMB Manipulate Structure
drag2 - RMB Resize/Rotate
Keyboard
S - Stereo Pair on/off
H - Help Screen
I - Data Info
A - Atoms On/Off
P - Polyhedra On/Off
B - Bonds On/Off
Help on Above

Post J E , Von Dreele R B , Buseck P R , Acta Crystallographica, Section B , 38 (1982) p.1056-1065, Symmetry and cation displacements in hollandites:, structure refinements of hollandite, cryptomelane and priderite, Locality: Chindwara, India, Note: -1M polytype, Note: Anisotropic displacement factors from ICSD

Physical Properties of Cryptomelane

Color:

Black, Gray, Blue gray.

Density:

4.36

Diaphaneity:

Opaque

Fracture:

Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).

Habit:

Botryoidal - "Grape-like" rounded forms (e.g.. malachite).

Habit:

Cryptocrystalline - Occurs as crystals too small to distinguish with the naked eye.

Habit:

Massive - Uniformly indistinguishable crystals forming large masses.

Hardness:

6-6.5 - Orthoclase-Pyrite

Luster:

Sub Metallic

Streak:

brownish black

Optical Properties of Cryptomelane

Optical Data:

NCalc= 2.44 - from Gladstone-Dale relationship (KC = 0.3304) where Ncalc=Dcalc*KC+1
NCalc= 2.44 - from Gladstone-Dale relationship (KC = 0.3304) where Ncalc=Dmeas*KC+1

Calculated Properties of Cryptomelane

Electron Density:

Bulk Density (Electron Density)=4.11 gm/cc
note: Specific Gravity of Cryptomelane =4.35 gm/cc.

Fermion Index:

Fermion Index = 0.0001736569
Boson Index = 0.9998263431

Photoelectric:

PE_Cryptomelane= 16.25 barns/electron
U=PE_Cryptomelane x r_electron= 66.76 barns/cc.

Radioactivity:

GRapi = 72.57 (Gamma Ray American Petroleum Institute Units)
Concentration of Cryptomelane per GRapi unit = 1.38 (%)

Estimated Radioactivity from Cryptomelane - barely detectable

Cryptomelane Classification

Dana Class:

07.09.01.02 (07)Multiple Oxides

(07.09)Dana Type

(07.09.01)Cryptomelane Group (Hard black, fine-grained)

07.09.01.01 Hollandite Ba(Mn,Mn)8O16 I2/m 2/m

07.09.01.02 Cryptomelane K(Mn,Mn)8O16 I2/m 2/m

07.09.01.03 Manjiroite (Na,K)(Mn,Mn)8O16•n(H2O) I 4/m 4/m

07.09.01.04 Coronadite Pb(Mn,Mn)8O16 I2/m 2/m

07.09.01.05 Strontiomelane! SrMn6Mn2O16 P 2₁/m 2/m

07.09.01.06 Henrymeyerite! BaFeTi7O16 I 4/m 4/m

Strunz Class:

04.DK.10 04 - OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodate

04.D - Metal:Oxygen = 1:2 and similar

04.DK -With large (± medium-sized) cations; tunnel structures

04.DK.10 Cryptomelane K(Mn,Mn)8O16 I2/m 2/m

04.DK.10 Todorokite (Na,Ca,K)2(Mn,Mn)6O12•3-4.5(H2O) P 2/m 2/m

04.DK.10 Romanechite (Ba,H2O)2(Mn,Mn)5O10 C 2/m 2/m

04.DK.10 Strontiomelane! SrMn6Mn2O16 P 2₁/m 2/m

Other Cryptomelane Information

References:

NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990)

See Also:

Links to other databases for Cryptomelane :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - Ecole des Mines de Paris
4 - Franklin Minerals(Dunn)
5 - Google Images
6 - Google Scholar
7 - Handbook of Mineralogy (MinSocAm)
8 - Handbook of Mineralogy (UofA)
9 - MinDAT
10 - MinMax(Deutsch)
11 - MinMax(English)
12 - Mineralienatlas (Deutsch)
13 - QUT Mineral Atlas
14 - Ruff.Info
15 - WWW-MINCRYST
16 - theimage

Search for Cryptomelane using:

[ALTAVISTA] [AOL] [All-The-Web] [HotBot] [Ixquick] [MAMMA] [MSN.COM] [Netscape] [Scirus] [Teoma] [Wikipedia] [YAHOO]

Visit our Advertisers for Cryptomelane :

AA Mineral Specimens

B & L Fine Minerals

Crystalarium.com

Dan Weinrich Fine Minerals

Dan Weinrich Auctions

Dakota Matrix

Desert Winds Gems and Minerals

John Betts Fine Minerals

Mason's Minerals

Mineral News

Mineral of the Month Club

Wrights Rock Shop

Translate Cryptomelane Mineral Data :

Ask about Cryptomelane here :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
Original Rockhounds Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Mineral Discussion Forum from Fabre Minerals - also available in Español

Print or Cut-and-Paste your Cryptomelane Specimen Label here :

Cryptomelane

K(Mn++++,Mn++)8O16
Dana No: 07.09.01.02 Strunz No: 04.DK.10
Locality:

Notes: