Medenbachite Mineral Data

Medenbachite Mineral Data +

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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.

Synonym:

ICSD 81357

IMA1993-048

PDF 49-1823

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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 - PinacoidalH-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),

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Crystal Structure:

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Krause W , Bernhardt H J , Gebert W , Graetsch H , Belendorff K , Petitjean K , American Mineralogist , 81 (1996) p.505-512, Medenbachite, Bi2Fe(Cu,Fe)(O,OH)2(OH)2(AsO4)2, a new mineral species: Its, description and crystal structure, Sample: 8.0.376, single Bi atom model

View Additional jPOWD Structure files for Medenbachite
[1] [2]

Physical Properties of Medenbachite

Cleavage:

None

Color:

Yellow, Brownish yellow.

Density:

5.9

Diaphaniety:

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= -0.015 (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

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:

r_electron=5.16 gm/cc
note: r_Medenbachite=5.90 gm/cc.

Fermion Index

Fermion Index = 0.00178
Boson Index = 0.99822

Photoelectric:

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

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Medenbachite is Not Radioactive

Medenbachite Classification

Dana Class:

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

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

(41.4.9)Medenbachite Group

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

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

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

Strunz Class:

VII/B.37-20 VII - Phosphates, Arsenates and Vanadates

VII/B - Waterfree phosphates with unfamiliar anions F, Cl, O, OH. cations of medium and big size: Mg, Cu, Zn, and Ca, Na, K, Ba, Pb

VII/B.37 - Paulkellerite series

VII/B.37-05 Brendelite! (Bi,Pb)2Fe(PO4)(O,OH)3 C 2/m 2/m

VII/B.37-10 Paulkellerite Bi2Fe(PO4)O2(OH)2 C 2/c 2/m

VII/B.37-15 Neustadtelite! Bi2Fe(Fe,Co)(O,OH)2(OH)2(AsO4)2 P1 1

VII/B.37-17 Cobaltneustadtelite! Bi2Fe(Co,Fe)(O,OH)2(OH)2(AsO4)2 P1 1

VII/B.37-20 Medenbachite Bi2Fe(Cu,Fe)(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 -Google Images 4 -Google Scholar 5 -Handbook of Mineralogy (UofA) 6 -MinDAT 7 -MinMax(Deutsch) 8 -MinMax(English) 9 -Mineralienatlas (Deutsch) 10 -QUT Mineral Atlas 11 - WWW-MINCRYST

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Medenbachite

Bi2Fe+++(Cu,Fe+++)(O,OH)2(OH)2(AsO4)2
Dana No: 41.4.9.1 Strunz No: VII/B.37-20
Locality:

Notes: