Guettardite Mineral Data

Guettardite Mineral Data +

General Guettardite Information

Chemical Formula:

Pb(Sb,As)2S4

Composition:

Molecular Weight = 536.82 gm

Antimony 24.95 % Sb

Arsenic 12.56 % As

Lead 38.60 % Pb

Sulfur 23.89 % S

______

100.00 %

Empirical Formula:

PbSb_1.1As_0.9S₄

Environment:

Low-temperature hydrothermal origin, in marbles.

IMA Status:

Approved IMA 1967

Locality:

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

Name Origin:

Named for Jean Etienne Guettard (17-15-1786), French geologist.

Synonym:

IMA1966-018

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Guettardite Crystallography

Axial Ratios:

a:b:c =2.5289:1:1.1028

Cell Dimensions:

a = 20.095, b = 7.946, c = 8.763, Z = 8; beta = 101.2° V = 1,372.58 Den(Calc)= 5.20

Crystal System:

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

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

By Intensity(I/I_o): 3.52(1), 2.795(0.9), 4.19(0.5),

Physical Properties of Guettardite

Cleavage:

[001] Perfect

Color:

Grayish black.

Density:

5.31

Diaphaniety:

Opaque

Fracture:

Brittle - Conchoidal - Very brittle fracture producing small, conchoidal fragments.

Habit:

Acicular - Occurs as needle-like crystals.

Habit:

Anhedral Grains - Granular minerals without the expression of crystal shapes

Hardness:

4 - Fluorite

Luster:

Metallic

Streak:

brownish

Optical Properties of Guettardite

RL Color:

White with reddish internal reflections.

RL Pleochroism:

Relatively strong.

Reflectivity

**Standardized Intensity (100%) Reflection Spectra of Guettardite in Air**
λ	R₁	R₂	∑ R₁(λ)	∑ R₂(λ)
470 nm	37.60	42.60
546 nm	36.10	41.20
589 nm	34.80	39.30
650 nm	33.80	36.70

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

Calculated Properties of Guettardite

Electron Density:

r_electron=4.49 gm/cc
note: r_Guettardite=5.20 gm/cc.

Fermion Index

Fermion Index = 0.08709
Boson Index = 0.91291

Photoelectric:

PE_Guettardite= 781.87 barns/electron
U=PE_Guettardite x r_electron=3,511.20 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Guettardite is Not Radioactive

Guettardite Classification

Dana Class:

3.7.8.2 (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.25-40 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 Guettardite Information

References:

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

See Also:

Links to other databases for Guettardite :
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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Guettardite

Pb(Sb,As)2S4
Dana No: 3.7.8.2 Strunz No: II/E.25-40
Locality:

Notes: