Psilomelane Mineral Data

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General Psilomelane Information

Chemical Formula:

(Ba,H2O)2Mn5O10

Composition:

Molecular Weight = 590.03 gm

Barium 23.27 % Ba 25.99 % BaO

Manganese 46.56 % Mn 66.89 % Mn₂O₃

Hydrogen 0.34 % H 3.05 % H₂O

Oxygen 29.83 % O

______ ______

100.00 % 95.93 % = TOTAL OXIDE

Empirical Formula:

Ba•(H₂O)Mn³⁺₅O₁₀

Environment:

General term for hard, black Mn oxides. Romanechite is one of the most common species.

IMA Status:

Discredited IMA 1982

Locality:

Common world wide. Link to MinDat.org Location Data.

Name Origin:

Named in 1758 from the Greek psilos - "smooth" and melas - "black."

Name Pronunciation:

Psilomelane + Pronunciation

Psilomelane Image

Images:

Psilomelane

Comments: Banded massive psilomelane.
Location: Compton, Virginia, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Psilomelane Crystallography

Axial Ratios:

a:b:c =3.3194:1:4.809

Cell Dimensions:

a = 9.56, b = 2.88, c = 13.85, Z = 2; beta = 92.5° V = 380.97 Den(Calc)= 5.14

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: A2/m

Physical Properties of Psilomelane

Cleavage:

None

Color:

Iron black, Dark steel gray.

Density:

4.4 - 4.7, Average = 4.55

Diaphaneity:

Opaque

Fracture:

Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern.

Habit:

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

Habit:

Mammillary - Larger "breast-like" rounded forms resembling botryoidal (e.g. malachite).

Habit:

Reniform - "Kidney like" in shape (e.g.. hematite).

Hardness:

5-6 - Between Apatite and Orthoclase

Luminescence:

Non-fluorescent.

Luster:

Sub Metallic

Magnetism:

Nonmagnetic

Streak:

brownish black

Optical Properties of Psilomelane

Optical Data:

NCalc= 2.26 - from Gladstone-Dale relationship (KC = 0.245) where Ncalc=Dcalc*KC+1
NCalc= 2.11 - from Gladstone-Dale relationship (KC = 0.245) where Ncalc=Dmeas*KC+1

Calculated Properties of Psilomelane

Electron Density:

Bulk Density (Electron Density)=4.72 gm/cc
note: Specific Gravity of Psilomelane =5.14 gm/cc.

Fermion Index:

Fermion Index = 0.04
Boson Index = 0.96

Photoelectric:

PE_Psilomelane= 114.11 barns/electron
U=PE_Psilomelane x rElectron Density= 538.80 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Psilomelane is Not Radioactive

Psilomelane Classification

Dana Class:

07.09.02.00 (07)Multiple Oxides

(07.09)Dana Type

(07.09.02)Dana Group

07.09.02.00 Psilomelane? (Ba,H2O)2Mn5O10 A2/m 2/m

07.09.02.01 Romanechite (Ba,H2O)2(Mn,Mn)5O10 C 2/m 2/m

Strunz Class:

04.XX.00 04 - OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodate

04.X - Unclassified Strunz OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, telluri

04.XX -Oxide

04.XX.00 Ashanite? (Nb,Ta,U,Fe,Mn)4O8 Pcan 2/m 2/m 2/m

04.XX.00 Methane hydrate-I! 46(H2O)•2(S)•6(L) P m3n 4/m 3 2/m

04.XX.00 Clinobirnessite* Na4Mn14O27•9(H2O) Mono

04.XX.00 Chubutite* Pb7O6Cl2 Unk Ortho

04.XX.00 Kleberite* FeTi6O13•4(H2O)(?) P 6₃mcm ? 6mm

04.XX.00 Hongquiite* TiO F m3m 4/m 3 2/m

04.XX.00 Psilomelane? (Ba,H2O)2Mn5O10 A2/m 2/m

04.XX.00 Struverite? (Ti,Ta,Fe)O2 P 4/mnm 4/m 2/m 2/m

04.XX.00 Ungursaite* NaCa5(Ta,Nb)24O65(OH) P 6₃/m,P 6₃ Hex

04.XX.00 Uhligite? Ca3(Ti,Al,Zr)9O20 Unk Cubic

04.XX.00 Scheteligite? (Ca,Y,Sb,Mn)2(Ti,Ta,Nb,W)2O6(O,OH) Unk Ortho

04.XX.00 Allendeite! Sc4Zr3O12 R 3 3

04.XX.00 IMA2000-016! (Ti,Fe,Mg,Mn)1-xTi2O5 Pban 2/m 2/m 2/m

04.XX.00 Methane hydrate-II! 136(H2O)•16(S)•8(L) F d3m 4/m 3 2/m

04.XX.00 IMA2000-026! (Mn,Li)4(Ta,Sn)4(Ta,Nb)8O32 C 2/c 2/m

04.XX.00 Methane hydrate-H! 34(H2O)•3(S)•2(M)•1(L) P 6/mmm 6/m 2/m 2/m

Other Psilomelane Information

References:

NAME( Duda&Rejl90) PHYS. PROP.(Mason68)

See Also:

Links to other databases for Psilomelane :
1 - Am. Min. Crystal Structure Database
2 - Amethyst Galleries' Mineral Gallery
3 - Athena
4 - Franklin Minerals(Palache)
5 - Glendale Community College
6 - Google Images
7 - Google Scholar
8 - MinDAT
9 - MinMax(Deutsch)
10 - MinMax(English)
11 - Mineralienatlas (Deutsch)
12 - QUT Mineral Atlas
13 - Ruff.Info
14 - WWW-MINCRYST

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Psilomelane

(Ba,H2O)2Mn5O10
Dana No: 07.09.02.00 Strunz No: 04.XX.00
Locality:

Notes: