Cosalite Mineral Data

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General Cosalite Information

Chemical Formula:

Pb2Bi2S5

Composition:

Molecular Weight = 992.69 gm

Bismuth 42.10 % Bi

Lead 41.75 % Pb

Sulfur 16.15 % S

______

100.00 %

Empirical Formula:

Pb₂Bi₂S₅

Environment:

In moderate-tempurature hydrothermal deposits, contact metasomatic replacements, epithermal replacements and pegmatites.

IMA Status:

Valid Species (Pre-IMA) 1868

Locality:

Silver Mine at Cosala, Sinaloa, Mexico. Link to MinDat.org Location Data.

Name Origin:

Named after its locality. Bjelkite is named after the Bjelke mine at Nordmark, Vermland, Sweden.

Name Pronunciation:

Cosalite

Synonym:

Bjelkite

ICSD 30780

PDF 42-1409

Cosalite Image

Images:

Cosalite

Comments: Metallic-lustered cosalite on matrix.
Location: Limestone Quarry, Hammerunterwiesenthal, Oberwiesenthal, Erzgebirge, Saxony, Germany. Scale: Picture size 8 mm.
© Thomas Witzke / Abraxas-Verlag

Cosalite Crystallography

Axial Ratios:

a:b:c =0.799:1:0.1698

Cell Dimensions:

a = 19.09, b = 23.89, c = 4.058, Z = 8; V = 1,850.69 Den(Calc)= 7.13

Crystal System:

Orthorhombic - DipyramidalH-M Symbol (2/m 2/m 2/m) Space Group: Pbnm

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

By Intensity(I/I_o): 3.44(1), 2.81(0.3), 3.37(0.25),

Forms:

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Forms: ( 0 1 0) ( 2 1 0) ( 1 2 0) ( 1 3 0) ( 1 0 0) ( 1 1 0) ( 6 3 2) ( 3 0 1)

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Crystal Structure:

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Srikrishnan T , Nowacki W , Zeitschrift fur Kristallographie , 140 (1974) p.114-136, A redetermination of the crystal structure of cosalite, Pb2Bi2S5, Locality: Cariboo gold mines, Wells, British Columbia, Canada

Physical Properties of Cosalite

Cleavage:

{010} Good

Color:

Gray, Steel gray, Silver white.

Density:

6.4 - 6.8, Average = 6.6

Diaphaneity:

Opaque

Fracture:

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

Habit:

Massive - Fibrous - Distinctly fibrous fine-grained forms.

Habit:

Radial - Crystals radiate from a center without producing stellar forms (e.g. stibnite)

Hardness:

2.5-3 - Finger Nail-Calcite

Luminescence:

Non-fluorescent.

Luster:

Metallic

Magnetism:

Nonmagnetic

Streak:

black

Optical Properties of Cosalite

RL Anisotrophism:

Weak but distinct in oil.

RL Color:

White with a trace of cream.

RL Pleochroism:

Weak.

Reflectivity

**Standardized Intensity (100%) Reflection Spectra of Cosalite in Air**
λ	R₁	R₂	∑ R₁(λ)	∑ R₂(λ)
400 nm	46.90	49.70
420 nm	46.20	49.00
440 nm	45.50	48.30
460 nm	44.70	47.50
480 nm	43.90	46.70
500 nm	43.00	46.00
520 nm	42.20	45.20
540 nm	41.50	44.50
560 nm	41.00	44.00
580 nm	40.50	43.60
600 nm	40.20	43.50
620 nm	40.10	43.40
640 nm	40.00	43.30
660 nm	40.00	43.20
680 nm	39.90	43.20
700 nm	39.90	43.10

**Calculated Relative Intensity Colors of Cosalite in Air**
Relative Intensity	0%	30%	60%	90%	100%	120%	150%	180%	210%	220%
R₁
R₂

Calculated Properties of Cosalite

Electron Density:

Bulk Density (Electron Density)=5.89 gm/cc
note: Specific Gravity of Cosalite =7.13 gm/cc.

Fermion Index:

Fermion Index = 0.09
Boson Index = 0.91

Photoelectric:

PE_Cosalite=1,597.07 barns/electron
U=PE_Cosalite x rElectron Density=9,406.17 barns/cc.

Radioactivity:

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

Cosalite Classification

Dana Class:

03.05.09.01 (03)Sulfides - Sulfosalts

(03.05)where 2.5 < z/y < 3 - (A+)i (A++)j [By Cz], A=metals, B=semi-metals, C=non-metals

(03.05.09)Cosalite Group

03.05.09.01 Cosalite Pb2Bi2S5 Pbnm 2/m 2/m 2/m

03.05.09.02 Veenite Pb2(Sb,As)2S5 P 2₁cn mm2

03.05.09.03 Dufrenoysite Pb2As2S5 P 2₁/m 2/m

Strunz Class:

02.JB.10 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.10 Cosalite Pb2Bi2S5 Pbnm 2/m 2/m 2/m

Other Cosalite Information

References:

NAME( Duda&Rejl90) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(AntBidBlaNic1)

See Also:

Links to other databases for Cosalite :
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
15 - WWW-MINCRYST

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

Cosalite

Pb2Bi2S5
Dana No: 03.05.09.01 Strunz No: 02.JB.10
Locality:

Notes: