Lengenbachite Mineral Data

Lengenbachite Mineral Data +

General Lengenbachite Information

Chemical Formula:

Pb6(Ag,Cu)2As4S13

Composition:

Molecular Weight = 2,140.02 gm

Copper 2.38 % Cu

Silver 6.05 % Ag

Arsenic 14.00 % As

Lead 58.09 % Pb

Sulfur 19.48 % S

______

100.00 %

Empirical Formula:

Pb₆Ag_1.2Cu_0.8As₄S₁₃

Environment:

Hydrothermal origin.

IMA Status:

Valid Species (Pre-IMA) 1905

Locality:

Lengenbach quarry, Binnental, Valais, Switzerland. Link to MinDat.org Location Data.

Name Origin:

Named after its locality.

Lengenbachite Image

Images:

Lengenbachite

Comments: Shiny, opaque crystalline spray of lengenbachite on white dolomite?.
Location: Lengenbach quarry, Binntal, Valais, Switzerland. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Images:

Lengenbachite

Comments: Metallic gray, thin plates and sheets of lengenbachite in a vug in white dolomite.
Location: Lengenbach quarry, Binntal, Valais, Switzerland. Scale: Picture width 1.2 cm.
© Walter Gabriel

Lengenbachite Crystallography

Axial Ratios:

a:b:c =1.5796:1:6.0068

Cell Dimensions:

a = 18.45, b = 11.68, c = 70.16, Z = 30; alpha = 90°, beta = 91.1°, gamma = 90° V = 15,116.41 Den(Calc)= 7.05

Crystal System:

TriclinicSpace Group: P1 or P1

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

By Intensity(I/I_o): 3.06(1), 2.84(0.9), 4.6(0.3),2.04(0.2), 2.93(0.2), 7.69(0.1), 9.31(0.1),

Physical Properties of Lengenbachite

Cleavage:

[100] Perfect, [h00] Distinct, [hk0] Distinct

Color:

Gray blue, Steel gray.

Density:

5.8 - 5.85, Average = 5.82

Diaphaniety:

Opaque

Fracture:

Flexible - Flexible fragments.

Habit:

Tabular - Form dimensions are thin in one direction.

Hardness:

1-2 - Between Talc and Gypsum

Luster:

Metallic

Streak:

brownish black

Optical Properties of Lengenbachite

RL Anisotrophism:

Weak.

Reflectivity

**Standardized Intensity (100%) Reflection Spectra of Lengenbachite in Air**
λ	R₁	R₂	∑ R₁(λ)	∑ R₂(λ)
400 nm	38.90	40.00
420 nm	38.50	39.80
440 nm	38.20	39.40
460 nm	37.60	39.00
480 nm	37.30	38.70
500 nm	36.80	38.30
520 nm	36.30	37.90
540 nm	35.90	37.40
560 nm	35.50	36.90
580 nm	35.30	36.50
600 nm	35.10	36.10
620 nm	34.70	35.70
640 nm	34.20	35.20
660 nm	33.50	34.40
680 nm	32.80	33.70
700 nm	32.00	32.90

**Calculated Relative Intensity Colors of Lengenbachite in Air**
Relative Intensity	0%	30%	60%	90%	100%	120%	150%	180%	210%	240%	260%
R₁
R₂

Calculated Properties of Lengenbachite

Electron Density:

r_electron=6.01 gm/cc
note: r_{Lengenbachite}=7.05 gm/cc.

Fermion Index

Fermion Index = 0.12984
Boson Index = 0.87016

Photoelectric:

PE_{Lengenbachite}=1,075.90 barns/electron
U=PE_{Lengenbachite} x r_electron=6,462.18 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Lengenbachite is Not Radioactive

Lengenbachite Classification

Dana Class:

3.3.7.1 (3)Sulfides - Sulfosalts

(3.3)where 3 < z/y < 4 - (A+)i (A++)j [By Cz], A=metals, B=semi-metals, C=non-metals

(3.3.7)Dana Group

3.3.7.1 Lengenbachite Pb6(Ag,Cu)2As4S13 P1 or P1 Tri

Strunz Class:

II/E.15-50 II - Sulfides and sulphosalts

II/E - Sulfosalts (S : As,Sb,Bi = x) Lead-Sulfosalts with Arsen and Antimon x = 3.8 - 3.1

II/E.15 - Jordanite - Lengenbachite series

II/E.15-10 Jordanite Pb14(As,Sb)6S23 P 2₁/m 2/m

II/E.15-20 Geocronite Pb14(Sb,As)6S23 P 2₁/m 2/m

II/E.15-30 Gratonite Pb9As4S15 R 3m 3m

II/E.15-40 Meneghinite Pb13CuSb7S24 Pbnm 2/m 2/m 2/m

II/E.15-45 Tsugaruite! Pb4As2S7 Pba2 or Pbam Ortho

II/E.15-50 Lengenbachite Pb6(Ag,Cu)2As4S13 P1 or P1 Tri

Other Lengenbachite Information

References:

NAME( AntBidBlaNic1) PHYS. PROP.(AntBidBlaNic1) OPTIC PROP.(AntBidBlaNic1)

See Also:

Links to other databases for Lengenbachite :
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 -École des Mines de Paris

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Lengenbachite

Pb6(Ag,Cu)2As4S13
Dana No: 3.3.7.1 Strunz No: II/E.15-50
Locality:

Notes: