Gratonite Mineral Data

General Gratonite Information

Chemical Formula:

Pb9As4S15

Composition:

Molecular Weight = 2,645.48 gm

Arsenic 11.33 % As

Lead 70.49 % Pb

Sulfur 18.18 % S

______

100.00 %

Empirical Formula:

Pb₉As₄S₁₅

Environment:

In vugs in hydrothermal copper ores.

IMA Status:

Valid Species (Pre-IMA) 1939

Locality:

In the Excelsior mine, Cerro de Pasco, Peru, in large crystals. Link to MinDat.org Location Data.

Name Origin:

For Louis Carly Graton (1880-1970), Professor of Economic Geology, Harvard University, Cambridge, Massachusetts, USA.

Name Pronunciation:

Gratonite + Pronunciation

Synonym:

ICSD 18097

PDF 44-1412

Gratonite Image

Images:

Gratonite

Comments: Crystal cluster of gratonite. The largest crystal is 2.5 mm across.
Location: Excelsior mine, Cerro de Pasco, Pasco dept., Peru. Scale: 1.5 x 1 cm.
© John Veevaert

Gratonite Crystallography

Axial Ratios:

a:c = 1:0.4402

Cell Dimensions:

a = 17.701, c = 7.792, Z = 3; V = 2,114.34 Den(Calc)= 6.23

Crystal System:

Trigonal - Ditrigonal PyramidalH-M Symbol (3m) Space Group: R 3m

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

By Intensity(I/I_o): 3.43(1), 3.75(0.6), 2.734(0.5),

Forms:

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Forms: ( 1 0 1) ( 4 0 1) ( 0 0 1) ( 1 1 0) ( 1 0 0) ( 0 2 1)

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Crystal Structure:

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Ribar B , Nowacki W , Zeitschrift fur Kristallographie , 128 (1969) p.321-338, Neubestimmung der kristallstruktur von gratonit, Pb9As4S15, Locality: Wiesloch, Germany

Physical Properties of Gratonite

Cleavage:

None

Color:

Lead gray, Dark lead gray.

Density:

6.22

Diaphaneity:

Opaque

Fracture:

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

Hardness:

2.5 - Finger Nail

Luster:

Metallic

Streak:

black

Optical Properties of Gratonite

Optical Data:

RL Color:

White, distinctly yellow against galena.

RL Pleochroism:

Very weak.

Reflectivity

**Standardized Intensity (100%) Reflection Spectra of Gratonite in Air**
λ	R₁	R₂	∑ R₁(λ)	∑ R₂(λ)
400 nm	36.90	37.80
420 nm	36.30	37.20
440 nm	35.70	36.60
460 nm	35.30	36.10
480 nm	35.10	35.70
500 nm	34.80	35.40
520 nm	34.50	35.00
540 nm	34.20	34.80
560 nm	34.10	34.60
580 nm	34.00	34.50
600 nm	33.90	34.50
620 nm	33.80	34.40
640 nm	33.70	34.20
660 nm	33.50	33.80
680 nm	33.00	33.40
700 nm	32.40	32.70

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

Calculated Properties of Gratonite

Electron Density:

Bulk Density (Electron Density)=5.23 gm/cc
note: Specific Gravity of Gratonite =6.23 gm/cc.

Fermion Index:

Fermion Index = 0.15
Boson Index = 0.85

Photoelectric:

PE_Gratonite=1,299.32 barns/electron
U=PE_Gratonite x rElectron Density=6,792.88 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Gratonite is Not Radioactive

Gratonite Classification

Dana Class:

03.03.02.01 (03)Sulfides - Sulfosalts

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

(03.03.02)Dana Group

03.03.02.01 Gratonite Pb9As4S15 R 3m 3m

Strunz Class:

02.JB.55 02 - SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulf

02.J - Sulfosalts of PbS Archetype

02.JB -Galena derivatives, with Pb

02.JB.55 Gratonite Pb9As4S15 R 3m 3m

Other Gratonite Information

References:

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

See Also:

Links to other databases for Gratonite :
1 - Am. Min. Crystal Structure Database
2 - Amethyst Galleries' Mineral Gallery
3 - Athena
4 - EUROmin Project
5 - Ecole des Mines de Paris
6 - GeoScienceWorld
7 - Google Images
8 - Google Scholar
9 - Handbook of Mineralogy (MinSocAm)
10 - Handbook of Mineralogy (UofA)
11 - HyperPhysics
12 - MinDAT
13 - Mineralienatlas (Deutsch)
14 - Online Mineral Museum
15 - QUT Mineral Atlas
16 - Ruff.Info

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Ask about Gratonite here :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
Original Rockhounds Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Mineral Discussion Forum from Fabre Minerals - also available in Español

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

Gratonite

Pb9As4S15
Dana No: 03.03.02.01 Strunz No: 02.JB.55
Locality:

Notes: