Gebhardite Mineral Data

Gebhardite Mineral Data +

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General Gebhardite Information

Chemical Formula:

Pb8(As+++2O5)2OCl6

Composition:

Molecular Weight = 2,346.00 gm

Arsenic 12.77 % As 16.87 % As₂O₃

Lead 70.66 % Pb 76.11 % PbO

Chlorine 9.07 % Cl 9.07 % Cl

- % Cl -2.05 % -O=Cl₂

Oxygen 7.50 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Pb₈As₄O₁₁Cl₆

IMA Status:

Approved IMA 1983

Locality:

Link to MinDat.org Location Data.

Synonym:

ICSD 40343

PDF 36-611

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Gebhardite Crystallography

Axial Ratios:

a:b:c =0.6003:1:3.0526

Cell Dimensions:

a = 6.724, b = 11.2, c = 34.19, Z = 4; beta = 85.2° V = 2,565.78 Den(Calc)= 6.07

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: P 2₁/c

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

By Intensity(I/I_o): 6.7(1), 3.68(0.8), 3.72(0.8),

Crystal Structure:

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Klaska R , Gebert W , Zeitschrift fur Kristallographie , 159 (1982) p.75-76, Polytypie und struktur von gebhardit - Pb8OCl6(As2O5)2, Locality: Tsumeb mine, Tsumeb, Namibia

Physical Properties of Gebhardite

Cleavage:

[001] Perfect, [010] Good

Color:

Light brown.

Density:

Diaphaniety:

Transparent

Hardness:

3 - Calcite

Luster:

Adamantine

Streak:

white

Optical Properties of Gebhardite

Gladstone-Dale:

CI meas= -0.081 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= -0.069 (Fair) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1812,KPDmeas= 0.1833,KC= 0.1695

Optical Data:

Biaxial (-), a=2.08, g=2.12, bire=0.0400

Calculated Properties of Gebhardite

Electron Density:

r_electron=5.06 gm/cc
note: r_Gebhardite=6.07 gm/cc.

Fermion Index

Fermion Index = 0.15618
Boson Index = 0.84382

Photoelectric:

PE_Gebhardite=1,311.50 barns/electron
U=PE_Gebhardite x r_electron=6,637.39 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Gebhardite is Not Radioactive

Gebhardite Classification

Dana Class:

46.2.5.1 (46)Basic or Halogen-Containing Antimonites, Arsenites and Phosphites

(46.2)with miscellaneous formulae

(46.2.5)Dana Group

46.2.5.1 Gebhardite Pb8(As2O5)2OCl6 P 2₁/c 2/m

Strunz Class:

IV/J.11-20 IV - Oxides

IV/J - Arsenides with [As2O5]4- groups

IV/J.11 - Paulmooreite - Gebhardite series

IV/J.11-10 Paulmooreite Pb2As2O5 P 2₁ 2

IV/J.11-20 Gebhardite Pb8(As2O5)2OCl6 P 2₁/c 2/m

Other Gebhardite Information

References:

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

See Also:

Links to other databases for Gebhardite :
1 -Am. Min. Crystal Structure Database 2 -Athena 3 - EUROmin Project 4 -Google Images 5 -Google Scholar 6 -Handbook of Mineralogy (UofA) 7 -MinDAT 8 -MinMax(Deutsch) 9 -MinMax(English) 10 -Mineralienatlas (Deutsch) 11 -QUT Mineral Atlas 12 - WWW-MINCRYST 13 -École des Mines de Paris

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

Gebhardite

Pb8(As+++2O5)2OCl6
Dana No: 46.2.5.1 Strunz No: IV/J.11-20
Locality:

Notes: