Dukeite Mineral Data

General Dukeite Information

Chemical Formula:

Bi+++24Cr++++++8O57(OH)6(H2O)3

Composition:

Molecular Weight = 6,499.55 gm

Chromium 6.40 % Cr 12.31 % CrO₃

Bismuth 77.17 % Bi 86.03 % Bi₂O₃

Hydrogen 0.19 % H 1.66 % H₂O

Oxygen 16.25 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Bi₂₄Cr₈O₅₇(OH)₆(H₂O)₃

Environment:

Found on a specimen of pucherite.

IMA Status:

Approved IMA 1999 (Dana # Added)

Locality:

Found on a museum specimen labeled from the San Jose mine, Brejauba, Minas Gerais, Brazil. Corrected locality is Lavra da Posse, Sao Jose de Berjauba, Conceicao do Mato Dentro County, Link to MinDat.org Location Data.

Name Origin:

Named for Duke University, Duham, North Carolina, USA and for the Mary Duke Biddle Foundation.

Synonym:

ICSD 89799

IMA1999-021

Dukeite Image

Images:

Dukeite

Comments: SEM photomicrograph showing part of a dukeite sheave (AmMin, 85:1823).
Location: Found on a museum specimen labeled as originating from the São José Mine, Brejaúba, Minas Gerais, Brazil. Scale: See Image.
© American Mineralogist

Dukeite Crystallography

Axial Ratios:

a:c = 1:1.01499

Cell Dimensions:

a = 15.067, c = 15.293, Z = 2; V = 3,006.61 Den(Calc)= 7.18

Crystal System:

Trigonal - Ditrigonal PyramidalH-M Symbol (3m) Space Group: P 3₁c

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

By Intensity(I/I_o): 3.382(1), 2.681(0.7), 1.701(0.5),7.65(0.5), 2.106(0.4), 2.175(0.4), 3.812(0.4),

Crystal Structure:

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Burns P C , Roberts A C , Stirling J A R , Criddle A J , Feinglos M N , American Mineralogist , 85 (2000) p.1822-1827, Dukeite, Bi24Cr8O57(OH)6(H2O)3, a new mineral from Brejauba, Minas Gerais,, Brazil: Description and crystal structure

Physical Properties of Dukeite

Cleavage:

None

Color:

Yellow, Dirty yellow brown.

Diaphaneity:

Translucent to transparent

Fracture:

Brittle - Uneven - Very brittle fracture producing uneven fragments.

Habit:

Acicular - Occurs as needle-like crystals.

Habit:

Wheat Sheaf - Bundle shaped aggregates resembling wheat sheafs after hand reaping wheat.

Hardness:

3-4 - Calcite-Fluorite

Luster:

Resinous

Streak:

bright yellow

Optical Properties of Dukeite

Gladstone-Dale:

CI calc= -0.053 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.188,KC= 0.1785
Ncalc = 2.28

Optical Data:

Uniaxial (?), a=2.33, b=2.37, bire=0.0400.

RL Bireflectance:

Very weak.

RL Color:

Gray to purplish-gray with strong yellow internal reflections aligned with crystal direction.

RL Pleochroism:

Mid orange-brown.

Reflectivity

**Standardized Intensity (100%) Reflection Spectra of Dukeite in Air**
λ	R₁	R₂		∑ R₁(λ)	∑ R₂(λ)
400 nm	19.80	21.40

420 nm

19.45

20.85

440 nm

18.90

20.05

460 nm

18.15

19.00

470 nm

17.90

18.60

480 nm

17.50

18.20

500 nm

17.00

17.55

520 nm

16.70

17.30

540 nm

16.50

17.10

546 nm

16.45

17.00

560 nm

16.30

16.90

580 nm

16.20

16.70

589 nm

16.00

16.50

600 nm

15.95

16.45

620 nm

15.80

16.25

640 nm

15.70

16.20

650 nm

15.70

16.20

660 nm

15.60

16.10

680 nm

15.50

15.95

700 nm

15.35

15.80

**Standardized Intensity (100%) Reflection Spectra of Dukeite in Oil**
λ	R₁	R₂		∑ R₁(λ)	∑ R₂(λ)
400 nm	7.60	9.01

420 nm			7.34	8.43
440 nm			6.80	7.61
460 nm			6.34	6.94
470 nm			6.11	6.65
480 nm			5.85	6.41
500 nm			5.48	5.98
520 nm			5.47	5.92
540 nm			5.46	5.95
546 nm			5.43	5.94
560 nm			5.32	5.88
580 nm			5.27	5.82
589 nm			5.19	5.67
600 nm			5.20	5.64
620 nm			5.12	5.64
640 nm			5.06	5.58
650 nm			5.00	5.57
660 nm			5.01	5.56
680 nm			4.95	5.56
700 nm			4.90	5.58

**Calculated Relative Intensity Colors of Dukeite in Air**
Relative Intensity	0%	60%	100%	120%	180%	240%	300%	360%	420%	480%	540%	550%
R₁
R₂

**Calculated Relative Intensity Colors of Dukeite in Oil**
Relative Intensity	0%	100%	200%	300%	400%	500%	600%	700%	800%	900%	1000%
R₁
R₂

Calculated Properties of Dukeite

Electron Density: Bulk Density (Electron Density)=6.02 gm/cc
note: Specific Gravity of Dukeite =7.18 gm/cc.

Fermion Index: Fermion Index = 0.0061589959
Boson Index = 0.9938410041

Photoelectric: PE_Dukeite=1,483.23 barns/electron
U=PE_Dukeite x rElectron Density=8,926.62 barns/cc.

Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Dukeite is Not Radioactive

Dukeite Classification

Dana Class: 36.01.03.01 (36)Compound Chromates (36.01)with miscellaneous formulae (36.01.03)Dana Group

36.01.03.01 Dukeite! Bi24Cr8O57(OH)6(H2O)3 P 3₁c 3m

Strunz Class: 07.DF.80 07 - SULFATES (SELENATES, TELLURATES) 07.D - Sulfates (selenates, etc.) with additional anions, with H2O 07.DF -With large and medium-sized cations

07.DF.80 Dukeite! Bi24Cr8O57(OH)6(H2O)3 P 3₁c 3m

Other Dukeite Information

References: NAME( AmMin, Vol 85, p 1822) PHYS. PROP.(AmMin, Vol 85, p 1822) OPTIC PROP.(AmMin, Vol 85, p 1822)

See Also: Links to other databases for Dukeite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - GeoScienceWorld
4 - Google Images
5 - Google Scholar
6 - MinDAT
7 - Mineralienatlas (Deutsch)
8 - Online Mineral Museum
9 - QUT Mineral Atlas
10 - Ruff.Info
11 - WWW-MINCRYST

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

Dukeite

Bi+++24Cr++++++8O57(OH)6(H2O)3
Dana No: 36.01.03.01 Strunz No: 07.DF.80
Locality:

Notes: