Medenbachite Mineral Data

General Medenbachite Information

Chemical Formula:

Bi2Fe+++(Cu,Fe+++)(O,OH)2(OH)2(AsO4)2

Composition:

Molecular Weight = 879.78 gm

Iron 7.93 % Fe 11.34 % Fe₂O₃

Copper 5.42 % Cu 6.78 % CuO

Bismuth 47.51 % Bi 52.96 % Bi₂O₃

Arsenic 17.03 % As 26.12 % As₂O₅

Hydrogen 0.29 % H 2.56 % H₂O

Oxygen 21.82 % O

______ ______

100.00 % 99.77 % = TOTAL OXIDE

Empirical Formula:

Bi₂Fe³⁺Cu_0.75Fe³⁺_0.25O_1.5(OH)_2.5(AsO₄)₂

Environment:

In a silicified barite vein.

IMA Status:

Approved IMA 1993 (Dana # Added)

Locality:

In a quarry near the Borstein cliff, about 1 km east of the town of Reichenbach, Odenwald, Hesse, Germany. Link to MinDat.org Location Data.

Name Origin:

Named for Dr. Olaf Medenbach (1949-) of the University of Bochum, Germany.

Name Pronunciation:

Medenbachite + Pronunciation

Synonym:

ICSD 81357

IMA1993-048

PDF 49-1823

Medenbachite Image

Images:

Medenbachite

Comments: SEM image of tabular plates of mendenbachite crystals. (AmMin, v81:505).
Location: Silicified barite vein from Reichenbach near Bensheim, Odenwald, Hesse, Germany. Scale: Scale Bar 20 µm.
© American Mineralogist

Medenbachite Crystallography

Axial Ratios:

a:b:c =0.7416:1:1.4594

Cell Dimensions:

a = 4.57, b = 6.162, c = 8.993, Z = 1; alpha = 94.55°, beta = 99.683°, gamma = 94.283° V = 248.16 Den(Calc)= 5.89

Crystal System:

Triclinic - Pinacoidal H-M Symbol ( 1) Space Group: P1

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

By Intensity(I/I_o): 3.749(1), 3.596(0.77), 2.903(0.69),

Forms:

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Forms: ( 1 3 1) ( 0 1 1) ( 1 1 0) ( 1 0 1) ( 0 0 1)

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Physical Properties of Medenbachite

Cleavage:

None

Color:

Yellow, Brownish yellow.

Density:

5.9

Diaphaneity:

Transparent to translucent

Fracture:

Brittle - Conchoidal - Very brittle fracture producing small, conchoidal fragments.

Habit:

Crystalline - Fine - Occurs as well-formed fine sized crystals.

Habit:

Tabular - Form dimensions are thin in one direction.

Hardness:

4.5 - Between Fluorite and Apatite

Luster:

Vitreous - Adamantine

Streak:

light yellow

Optical Properties of Medenbachite

Gladstone-Dale:

CI meas= -0.014 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.016 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1822,KPDmeas= 0.1819,KC= 0.1793
Ncalc = 2.06

Optical Data:

Biaxial (-), a=2.03, b=2.09, g=2.1, bire=0.0700, 2V(Calc)=42, 2V(Meas)=43. Dispersion r > v.

Calculated Properties of Medenbachite

Electron Density:

Bulk Density (Electron Density)=5.16 gm/cc
note: Specific Gravity of Medenbachite =5.90 gm/cc.

Fermion Index:

Fermion Index = 0.0017878211
Boson Index = 0.9982121789

Photoelectric:

PE_Medenbachite= 891.97 barns/electron
U=PE_Medenbachite x rElectron Density=4,602.93 barns/cc.

Radioactivity:

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

Medenbachite Classification

Dana Class:

41.04.09.01 (41)Anhydrous Phosphates, etc. Containing Hydroxyl or Halogen

(41.04)where (A B)5 (XO4)2 Zq

(41.04.09)Medenbachite Group

41.04.09.01 Medenbachite! Bi2Fe(Cu,Fe)(O,OH)2(OH)2(AsO4)2 P1 1

41.04.09.02 Neustadtelite! Bi2Fe(Fe,Co)(O,OH)2(OH)2(AsO4)2 P1 1

41.04.09.03 Cobaltneustadtelite! Bi2Fe(Co,Fe)(O,OH)2(OH)2(AsO4)2 P1 1

Strunz Class:

08.BK.10 08 - PHOSPHATES, ARSENATES, VANADATES

08.B - Phosphates, etc. with Additional Anions, without H2O

08.BK -With medium-sized and large cations, (OH, etc.)

08.BK.10 Medenbachite! Bi2Fe(Cu,Fe)(O,OH)2(OH)2(AsO4)2 P1 1

08.BK.10 Cobaltneustadtelite! Bi2Fe(Co,Fe)(O,OH)2(OH)2(AsO4)2 P1 1

08.BK.10 Neustadtelite! Bi2Fe(Fe,Co)(O,OH)2(OH)2(AsO4)2 P1 1

Other Medenbachite Information

References:

NAME( MinRec) PHYS. PROP.(Am.Min.,Vol.81,1996, Vol 87, p 726) OPTIC PROP.(Am.Min.,Vol.81,1996)

See Also:

Links to other databases for Medenbachite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - GeoScienceWorld
4 - Google Images
5 - Google Scholar
6 - Handbook of Mineralogy (MinSocAm)
7 - Handbook of Mineralogy (UofA)
8 - MinDAT
9 - Mineralienatlas (Deutsch)
10 - Online Mineral Museum
11 - QUT Mineral Atlas
12 - Ruff.Info
13 - WWW-MINCRYST

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Medenbachite

Bi2Fe+++(Cu,Fe+++)(O,OH)2(OH)2(AsO4)2
Dana No: 41.04.09.01 Strunz No: 08.BK.10
Locality:

Notes:

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