Benjaminite Mineral Data

Benjaminite Mineral Data +

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General Benjaminite Information

Chemical Formula:

(Ag,Cu)3(Bi,Pb)7S12

Composition:

Molecular Weight = 2,134.46 gm

Copper 2.23 % Cu

Silver 11.37 % Ag

Bismuth 48.95 % Bi

Lead 19.41 % Pb

Sulfur 18.03 % S

______

100.00 %

Empirical Formula:

Ag_2.25Cu_0.75Bi₅Pb₂S₁₂

Environment:

In a quartz vein near the contact of a soda-granite and an intrusive rhyolite.

IMA Status:

Valid Species (Pre-IMA) 1924

Locality:

Outlaw Mine, 12 miles north of Manhattan, Nye Co. Nevada, USA. Link to MinDat.org Location Data.

Name Origin:

For Dr. Marcus Benjamin (1857-1932), of the U.S. National Museum.

Synonym:

ICSD 100734

PDF 29-577

Benjaminite Image

Images:

Benjaminite Krupkaite Friedrichite

Comments: Crystals of a mixture of friedrichite, krupkaite, and benjaminite, with quartz crystals.
Location: Estela Mine, Julcani District, Junin, Peru. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Benjaminite Crystallography

Axial Ratios:

a:b:c =3.2754:1:4.9898

Cell Dimensions:

a = 13.246, b = 4.044, c = 20.179, Z = 2; beta = 103.21° V = 1,052.32 Den(Calc)= 6.74

Crystal System:

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

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

By Intensity(I/I_o): 2.851(1), 3.427(0.8), 3.539(0.8),

Crystal Structure:

Mouse
drag1 - LMB Manipulate Structure
drag2 - RMB Resize/Rotate
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H - Help Screen
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Makovicky E , Mumme W G , The Canadian Mineralogist , 17 (1979) p.607-618, The crystal structure of benjaminite Cu.5Pb.4Ag2.3Bi6.8S12

Physical Properties of Benjaminite

Cleavage:

[hk0] Fair

Color:

Grayish yellow, Copper.

Density:

6.7

Diaphaniety:

Opaque

Hardness:

3.5 - Copper Penny

Luminescence:

Non-fluorescent.

Luster:

Metallic

Magnetism:

Nonmagnetic

Optical Properties of Benjaminite

RL Anisotrophism:

Strong.

RL Color:

Creamy white to very pale brownish.

Reflectivity

**Standardized Intensity (100%) Reflection Spectra of Benjaminite in Air**
λ	R₁	R₂	∑ R₁(λ)	∑ R₂(λ)
400 nm	44.20	47.20
420 nm	44.80	47.80
440 nm	45.20	48.60
460 nm	45.20	49.00
480 nm	45.00	49.20
500 nm	44.80	49.20
520 nm	44.50	49.00
540 nm	44.00	48.60
560 nm	43.60	48.00
580 nm	43.30	47.60
600 nm	43.10	47.20
620 nm	43.00	46.80
640 nm	42.80	46.30
660 nm	42.70	45.90
680 nm	42.60	45.60
700 nm	42.50	45.20

**Calculated Relative Intensity Colors of Benjaminite in Air**
Relative Intensity	0%	30%	60%	90%	100%	120%	150%	180%	210%
R₁
R₂

Calculated Properties of Benjaminite

Electron Density:

r_electron=5.67 gm/cc
note: r_Benjaminite=6.74 gm/cc.

Fermion Index

Fermion Index = 0.04425
Boson Index = 0.95575

Photoelectric:

PE_Benjaminite=1,322.77 barns/electron
U=PE_Benjaminite x r_electron=7,505.95 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Benjaminite is Not Radioactive

Benjaminite Classification

Dana Class:

3.8.10.3 (3)Sulfides - Sulfosalts

(3.8)where 1 < z/y <2 - (A+)i (A++)j [By Cz], A=metals, B=semi-metals, C=non-metals

(3.8.10)Pavonite Group (Monoclinic: C/2c bismuth sulfosalts)

3.8.10.1 Pavonite (Ag,Cu)(Bi,Pb)3S5 C 2/c 2/m

3.8.10.2 Makovickyite Ag1.5Bi5.5S9 C 2/c 2/m

3.8.10.3 Benjaminite (Ag,Cu)3(Bi,Pb)7S12 C 2/c 2/m

3.8.10.4 Mummeite Ag3CuPbBi6S13orAg2Cu2Pb2Bi6S13 C 2/c 2/m

3.8.10.5 Borodaevite Ag5(Bi,Sb)9S16 C 2/c 2/m

3.8.10.6 Cupropavonite AgPbCu2Bi5S10 C 2/c 2/m

3.8.10.7 Cupromakovickyite! Cu4AgPb2Bi9S18 C 2/m 2/m

3.8.10.8 Kudriavite! (Cd,Pb)Bi2S4 C 2/m 2/m

Strunz Class:

II/E.09-10 II - Sulfides and sulphosalts

II/E - Sulfosalts (S : As,Sb,Bi = x) Sulfosalts with predominant Silver, x = 6.0 - 1.6

II/E.09 - Benjaminite - Kitaibelite series

II/E.09-05 Borodaevite Ag5(Bi,Sb)9S16 C 2/c 2/m

II/E.09-10 Benjaminite (Ag,Cu)3(Bi,Pb)7S12 C 2/c 2/m

II/E.09-20 Mummeite Ag3CuPbBi6S13orAg2Cu2Pb2Bi6S13 C 2/c 2/m

II/E.09-30 Pavonite (Ag,Cu)(Bi,Pb)3S5 C 2/c 2/m

II/E.09-40 Cupropavonite AgPbCu2Bi5S10 C 2/c 2/m

II/E.09-50 Kitaibelite* Ag10PbBi30S51 Mono ? Mono

II/E.09-60 Makovickyite Ag1.5Bi5.5S9 C 2/c 2/m

Other Benjaminite Information

References:

NAME( AntBidBlaNic1) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(AntBidBlaNic1)

See Also:

Links to other databases for Benjaminite :
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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Benjaminite

(Ag,Cu)3(Bi,Pb)7S12
Dana No: 3.8.10.3 Strunz No: II/E.09-10
Locality:

Notes: