Pearceite Mineral Data

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General Pearceite Information

Chemical Formula:

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

Composition:

Molecular Weight = 2,096.80 gm

Copper 11.64 % Cu

Silver 62.50 % Ag

Antimony 4.82 % Sb

Arsenic 4.22 % As

Sulfur 16.82 % S

______

100.00 %

Empirical Formula:

Ag_12.15Cu_3.84As_1.18Sb_0.83S₁₁

Environment:

The arsenic analog of polybasite.

IMA Status:

Valid Species (Pre-IMA) 1896

Locality:

Aspen, Colorado. Link to MinDat.org Location Data.

Name Origin:

Named after the American chemist, R. Pearce (1837-1927).

Name Pronunciation:

Pearceite + Pronunciation

Synonym:

Pearceite-Tac - Suggested nomenclature from AmMin v92:918

Pearceite Image

Images:

Pearceite

Comments: Crystals of metallic pearceite to 0.75 mm scattered in vug.
Location: Sarbaiskoe, Kazakhstan. Scale: 4x3x3 cm.
© Tom Loomis / Dakota Matrix

Pearceite Crystallography

Axial Ratios:

a:c = 1:1.60921

Cell Dimensions:

a = 7.3876, c = 11.8882, Z = 1; V = 561.89 Den(Calc)= 6.20

Crystal System:

Trigonal - Hexagonal ScalenohedralH-M Symbol (3 2/m) Space Group: P 3m1

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

By Intensity(I/I_o): 3(1), 2.84(0.9), 3.11(0.5),

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

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Crystal Structure:

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Bindi L , Evain M , Menchetti S , Acta Crystallographica, Section B , 62 (2006) p.212-219, Temperature dependence of the silver distribution in the, crystal structure of natural pearcite, (Ag,Cu)16(As,Sb)2S11, Sample: T = 300 K, Locality: Clara mine, Black Forest, Germany

Physical Properties of Pearceite

Cleavage:

{001} Poor

Color:

Black.

Density:

6.15

Diaphaneity:

Opaque to subtranslucent

Fracture:

Conchoidal - Irregular - Irregular fracture producing small, conchoidal fragments.

Habit:

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

Habit:

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

Hardness:

3 - Calcite

Luminescence:

Non-fluorescent.

Luster:

Sub Metallic

Magnetism:

Nonmagnetic

Streak:

reddish black

Optical Properties of Pearceite

Gladstone-Dale:

CI meas= -1.009 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= -0.993 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2742,KPDmeas= 0.2764,KC= 0.1376
Ncalc = 1.85

Optical Data:

Biaxial (?), a=2.7

RL Anisotrophism:

Moderate, often dark violet.

RL Color:

White, with very dark red internal reflections.

RL Pleochroism:

Very weak in air, fair in oil.

Reflectivity

**Standardized Intensity (100%) Reflection Spectra of Pearceite in Air**
λ	R₁	R₂	∑ R₁(λ)	∑ R₂(λ)
400 nm	34.80	34.30
420 nm	34.20	34.20
440 nm	33.40	34.10
460 nm	32.50	33.80
480 nm	31.50	33.20
500 nm	30.60	32.80
520 nm	29.80	32.50
540 nm	29.30	32.30
560 nm	29.00	32.00
580 nm	29.00	31.70
600 nm	29.10	31.20
620 nm	29.10	30.70
640 nm	28.90	30.20
660 nm	28.60	29.80
680 nm	28.00	29.30
700 nm	27.40	29.10

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

Calculated Properties of Pearceite

Electron Density:

Bulk Density (Electron Density)=5.56 gm/cc
note: Specific Gravity of Pearceite =6.20 gm/cc.

Fermion Index:

Fermion Index = 0.0012616575
Boson Index = 0.9987383425

Photoelectric:

PE_Pearceite= 184.23 barns/electron
U=PE_Pearceite x rElectron Density=1,023.75 barns/cc.

Radioactivity:

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

Pearceite Classification

Dana Class:

03.01.08.01 (03)Sulfides - Sulfosalts

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

(03.01.08)Pearceite group

03.01.08.01 Pearceite [Ag9CuS4][(Ag,Cu)6(As,Sb)2S7] P 3m1 3 2/m

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

03.01.08.03 Cupropearceite [Cu6As2S7][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 Pearceite Information

References:

NAME( Duda&Rejl90) PHYS. PROP.(Dana8, AmMin 91:1953) OPTIC PROP.(AntBidBlaNic1)

See Also:

Links to other databases for Pearceite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - Google Images
6 - Google Scholar
7 - Handbook of Mineralogy (MinSocAm)
8 - Handbook of Mineralogy (UofA)
9 - MinDAT
10 - MinMax(Deutsch)
11 - MinMax(English)
12 - Mineralienatlas (Deutsch)
13 - QUT Mineral Atlas
14 - Ruff.Info

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

Pearceite

[Ag9CuS4] [(Ag,Cu)6(As,Sb)2S7]
Dana No: 03.01.08.01 Strunz No: 02.GB.15
Locality:

Notes: