Twinnite Mineral Data

Twinnite Mineral Data +

General Twinnite Information

Chemical Formula:

Pb(Sb,As)2S4

Composition:

Molecular Weight = 574.28 gm

Antimony 40.28 % Sb

Arsenic 1.30 % As

Lead 36.08 % Pb

Sulfur 22.33 % S

______

100.00 %

Empirical Formula:

PbSb_1.9As_0.1S₄

Environment:

In marble with other lead sulfantimonides.

IMA Status:

Valid Species (Pre-IMA) 1957

Locality:

Madoc, Ontario, Canada. Link to MinDat.org Location Data.

Name Origin:

Named for Robert M. Thompson (1918-1967), Canadian Mineralogist: Thompson means "son of Thomas," which is Aramaic for "twin."

Synonym:

IMA1966-017

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Twinnite Crystallography

Axial Ratios:

a:b:c =2.4537:1:1.073

Cell Dimensions:

a = 19.583, b = 7.981, c = 8.564, Z = 8; alpha = 89.767°, beta = 89.617°, gamma = 90.267° V = 1,338.43 Den(Calc)= 5.70

Crystal System:

Triclinic - PinacoidalH-M Symbol ( 1) Space Group: P1

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

By Intensity(I/I_o): 3.51(1), 2.344(0.8), 2.78(0.7),

Physical Properties of Twinnite

Cleavage:

[100] Perfect

Color:

Black.

Density:

5.26

Diaphaniety:

Opaque

Fracture:

Brittle - Generally displayed by glasses and most non-metallic minerals.

Habit:

Microscopic Crystals - Crystals visible only with microscopes.

Habit:

Twinning Common - Crystals are usually twinned.

Hardness:

3.5 - Copper Penny

Luster:

Metallic

Streak:

brownish black

Optical Properties of Twinnite

RL Color:

White.

RL Pleochroism:

Strong, displaying twin lamellae.

Reflectivity

**Standardized Intensity (100%) Reflection Spectra of Twinnite in Air**
λ	R₁	R₂	∑ R₁(λ)	∑ R₂(λ)
400 nm	39.10	45.20
420 nm	38.20	44.70
440 nm	37.30	44.20
460 nm	36.60	43.70
480 nm	36.20	43.20
500 nm	35.80	42.90
520 nm	35.50	42.50
540 nm	35.00	42.00
560 nm	34.40	41.40
580 nm	34.00	40.80
600 nm	33.50	40.00
620 nm	33.20	39.40
640 nm	32.80	38.70
660 nm	32.30	38.10
680 nm	31.70	37.50
700 nm	31.00	37.00

**Calculated Relative Intensity Colors of Twinnite in Air**
Relative Intensity	0%	30%	60%	90%	100%	120%	150%	180%	210%	240%	270%
R₁
R₂

Calculated Properties of Twinnite

Electron Density:

r_electron=4.89 gm/cc
note: r_Twinnite=5.70 gm/cc.

Fermion Index

Fermion Index = 0.08141
Boson Index = 0.91859

Photoelectric:

PE_Twinnite= 786.44 barns/electron
U=PE_Twinnite x r_electron=3,843.57 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Twinnite is Not Radioactive

Twinnite Classification

Dana Class:

3.7.8.3 (3)Sulfides - Sulfosalts

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

(3.7.8)Dana Group

3.7.8.1 Sartorite PbAs2S4 P 2₁/c 2/m

3.7.8.2 Guettardite Pb(Sb,As)2S4 P 2₁/a 2/m

3.7.8.3 Twinnite Pb(Sb,As)2S4 P1 1

3.7.8.4 Marumoite! Pb32As40S92 P 2₁ 2

Strunz Class:

II/E.25-50 II - Sulfides and sulphosalts

II/E - Sulfosalts (S : As,Sb,Bi = x) Lead-Sulfosalts with Arsen and Antimon x = 2.3 - 1.8

II/E.25 - Liveingite - Twinnite series

II/E.25-10 Liveingite Pb9As13S28 P 2₁ 2

II/E.25-20 Rathite Pb8Pb4-x(Tl2As2)x(Ag2As2)As16S40 P 2₁/n 2/m

II/E.25-30 Sartorite PbAs2S4 P 2₁/c 2/m

II/E.25-40 Guettardite Pb(Sb,As)2S4 P 2₁/a 2/m

II/E.25-50 Twinnite Pb(Sb,As)2S4 P1 1

Other Twinnite Information

References:

NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(AntBidBlaNic1)

See Also:

Links to other databases for Twinnite :
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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Print or Cut-and-Paste your Twinnite Specimen Label here :

Twinnite

Pb(Sb,As)2S4
Dana No: 3.7.8.3 Strunz No: II/E.25-50
Locality:

Notes: