Polybasite Mineral Data

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General Polybasite Information

Chemical Formula:

[Ag9CuS4] [(Ag,Cu)6(Sb,As)2S7]

Composition:

Molecular Weight = 2,154.03 gm

Copper 8.85 % Cu

Silver 65.10 % Ag

Antimony 7.07 % Sb

Arsenic 2.61 % As

Sulfur 16.38 % S

______

100.00 %

Empirical Formula:

Ag₉CuS₄Ag₄Cu₂Sb_1.25As_0.75S₇

Environment:

In silver viens of low to moderate temperature of formation.

IMA Status:

Valid Species (Pre-IMA) 1829

Locality:

Common world wide. Link to MinDat.org Location Data.

Name Origin:

From the Greek, poly, "many" and basis, "a base" in allusion to the basic character of the compound.

Name Pronunciation:

Polybasite + Pronunciation

Synonym:

Polybasite-M2a2b2c - Suggested nomenclature from AmMin v92:918

Polybasite-T2ac - Suggested nomenclature from AmMin v92:918

Polybasite Image

Images:

Polybasite

Comments: Lustrous, metallic steel-gray rosette of polybasite crystals.
Location: Guanajuato, Mexico. Scale: 18 x 16 x 8 mm.
© Dan Weinrich

Polybasite Crystallography

Axial Ratios:

a:b:c =1.732:1:1.5842

Cell Dimensions:

a = 26.12, b = 15.08, c = 23.89, Z = 16; beta = 90° V = 9,410.02 Den(Calc)= 6.08

Crystal System:

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

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

By Intensity(I/I_o): 3(1), 3.19(0.9), 2.88(0.8),

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

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Crystal Structure:

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Evain M , Bindi L , Menchetti S , Acta Crystallographica, Section B , 62 (2006) p.447-456, Structural compexity in minerals: twinning, polytypism and disorder, in the crystal structure of polybasite, (Ag,Cu)16(Sb,As)2S11, Sample: T = 120 K, Sample: polytype 221, Locality: Hidalgo, Mexico

Physical Properties of Polybasite

Cleavage:

{001} Poor

Color:

Black, Dark ruby red.

Density:

4.6 - 5, Average = 4.8

Diaphaneity:

Opaque

Fracture:

Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern.

Habit:

Granular - Generally occurs as anhedral to subhedral crystals in matrix.

Habit:

Massive - Granular - Common texture observed in granite and other igneous rock.

Habit:

Pseudo Hexagonal - Crystals show a hexagonal outline.

Hardness:

2.5-3 - Finger Nail-Calcite

Luminescence:

Non-fluorescent.

Luster:

Sub Metallic

Magnetism:

Nonmagnetic

Streak:

reddish black

Optical Properties of Polybasite

Optical Data:

NCalc= 1.84 - from Gladstone-Dale relationship (KC = 0.1378) where Ncalc=Dcalc*KC+1
NCalc= 1.66 - from Gladstone-Dale relationship (KC = 0.1378) where Ncalc=Dmeas*KC+1

Reflectivity

**Standardized Intensity (100%) Reflection Spectra of Polybasite in Air**
λ	R₁	R₂	∑ R₁(λ)	∑ R₂(λ)
400 nm	33.90	32.50
420 nm	33.60	32.80
440 nm	33.00	33.90
460 nm	31.90	33.80
480 nm	32.40	34.00
500 nm	31.90	33.80
520 nm	31.30	33.40
540 nm	30.80	32.80
560 nm	30.50	32.20
580 nm	30.20	31.70
600 nm	29.80	31.10
620 nm	29.30	30.50
640 nm	29.10	29.30
660 nm	27.30	29.10
680 nm	27.20	28.40
700 nm	26.90	27.80

**Calculated Relative Intensity Colors of Polybasite in Air**
Relative Intensity	0%	40%	80%	100%	120%	160%	200%	240%	280%	300%
R₁
R₂

Calculated Properties of Polybasite

Electron Density:

Bulk Density (Electron Density)=5.43 gm/cc
note: Specific Gravity of Polybasite =6.08 gm/cc.

Fermion Index:

Fermion Index = 0.0012281379
Boson Index = 0.9987718621

Photoelectric:

PE_Polybasite= 196.28 barns/electron
U=PE_Polybasite x rElectron Density=1,066.49 barns/cc.

Radioactivity:

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

Polybasite Classification

Dana Class:

03.01.07.02 (03)Sulfides - Sulfosalts

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

(03.01.07)Polybasite group

03.01.07.01 Arsenpolybasite [Ag9CuS4][(Ag,Cu)6(As,Sb)2S7] C 2/m 2/m

03.01.07.02 Polybasite [Ag9CuS4][(Ag,Cu)6(Sb,As)2S7] C 2/m 2/m

03.01.07.03 Selenopolybasite! [(Ag,Cu)6(Sb,As)2(S,Se)7][Ag9Cu(S,Se)2Se2] P 3m1 3m

03.01.07.04 Cupropolybasite! [Cu6Sb2S7][Ag9CuS4] P 3m1 3 2/m

Strunz Class:

02.GB.15 02 - SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulf

02.G - Sulfarsenites, sulfantimonites, sulfbismuthites

02.GB -Neso-sulfarsenites, etc

02.GB.15 Antimonpearceite [Ag9CuS4][(Ag,Cu)6(Sb,As)2S7] C 2/m 2/m

02.GB.15 Arsenpolybasite [Ag9CuS4][(Ag,Cu)6(As,Sb)2S7] C 2/m 2/m

02.GB.15 Polybasite [Ag9CuS4][(Ag,Cu)6(Sb,As)2S7] C 2/m 2/m

02.GB.15 Pearceite [Ag9CuS4][(Ag,Cu)6(As,Sb)2S7] P 3m1 3 2/m

02.GB.15 Cupropearceite [Cu6As2S7][Ag9CuS4] P 3m1 3 2/m

02.GB.15 Selenopolybasite! [(Ag,Cu)6(Sb,As)2(S,Se)7][Ag9Cu(S,Se)2Se2] P 3m1 3m

02.GB.15 Cupropolybasite! [Cu6Sb2S7][Ag9CuS4] P 3m1 3 2/m

Other Polybasite Information

References:

NAME( Ford32) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(AntBidBlaNic1)

See Also:

Links to other databases for Polybasite :
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 - MinDAT
12 - Mineralienatlas (Deutsch)
13 - Online Mineral Museum
14 - Philatelic Mineralogy
15 - QUT Mineral Atlas
16 - Ruff.Info

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

Polybasite

[Ag9CuS4] [(Ag,Cu)6(Sb,As)2S7]
Dana No: 03.01.07.02 Strunz No: 02.GB.15
Locality:

Notes: