Smithite Mineral Data

Smithite Mineral Data +

General Smithite Information

Chemical Formula:

AgAsS2

Composition:

Molecular Weight = 246.92 gm

Silver 43.69 % Ag

Arsenic 30.34 % As

Sulfur 25.97 % S

______

100.00 %

Empirical Formula:

AgAsS₂

Environment:

Of hydrothermal origin with other Ag-As sulfides.

IMA Status:

Valid Species (Pre-IMA) 1905

Locality:

Lengenbach quarry, Binnental, Valais, Switzerland. Link to MinDat.org Location Data.

Name Origin:

Named for George Frederick Smith (1872-1953), crystallographer of the British Museum, London, England.

Synonym:

ICSD 64984

PDF 42-554

Smithite Image

Images:

Smithite

Comments: Spheric, pseudo-hexagonal, reddish crystal of smithite with a gray sulfosalt on white dolomite.
Location: Lengenbach quarry, Binntal, Valais, Switzerland. Scale: Crystal size 0.5 mm.
© Walter Gabriel

Smithite Crystallography

Axial Ratios:

a:b:c =2.2164:1:1.9536

Cell Dimensions:

a = 17.2, b = 7.76, c = 15.16, Z = 24; beta = 101.2° V = 1,984.90 Den(Calc)= 4.96

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: A2/a

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

By Intensity(I/I_o): 2.82(1), 3.21(0.8), 2.72(0.6),

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Forms: [ 3 1 1] [ 3 1 1] [ 2 1 1] [ 4 1 1] [ 3 2 0] [ 1 0 1] [ 1 1 1] [ 1 0 0] [ 1 1 3] [ 5 1 1] [ 0 0 1]

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Crystal Structure:

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Hellner E , Burzlaff H , Naturwissenschaften , 51 (1964) p.35-36, Die struktur des smithits AgAsS2, Locality: Legenbach quarry, Binnatal, Switzerland

Physical Properties of Smithite

Cleavage:

[100] Perfect

Color:

Brown orange, Light red, Orange red.

Density:

4.9

Diaphaniety:

Subtranslucent to opaque

Fracture:

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

Habit:

Pseudo Hexagonal - Crystals show a hexagonal outline.

Habit:

Pyramidal - Crystals are shaped like pyramids.

Hardness:

1.5-2 - Talc-Gypsum

Luminescence:

Non-fluorescent.

Luster:

Sub Metallic

Streak:

vermilion red

Optical Properties of Smithite

Optical Data:

Biaxial (-), b=3.27, 2V(Meas)=~65.

Pleochroism (x):

slight.

Pleochroism (y):

slight.

Pleochroism (z):

slight.

Reflectivity

**Standardized Intensity (100%) Reflection Spectra of Smithite in Air**
λ	R₁	R₂	∑ R₁(λ)	∑ R₂(λ)
400 nm	40.70	44.00
420 nm	40.00	43.20
440 nm	39.30	42.40
460 nm	38.70	41.50
480 nm	37.90	40.40
500 nm	37.00	39.20
520 nm	36.00	38.00
540 nm	35.00	36.60
560 nm	33.80	35.40
580 nm	32.70	34.70
600 nm	32.00	34.00
620 nm	31.40	33.40
640 nm	31.00	32.90
660 nm	30.60	32.40
680 nm	30.40	31.80
700 nm	30.10	31.40

**Calculated Relative Intensity Colors of Smithite in Air**
Relative Intensity	0%	30%	60%	90%	100%	120%	150%	180%	210%	240%	270%
R₁
R₂

Calculated Properties of Smithite

Electron Density:

r_electron=4.50 gm/cc
note: r_Smithite=4.96 gm/cc.

Fermion Index

Fermion Index = 0.00194
Boson Index = 0.99806

Photoelectric:

PE_Smithite= 132.86 barns/electron
U=PE_Smithite x r_electron= 597.80 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Smithite is Not Radioactive

Smithite Classification

Dana Class:

3.7.3.1 (3)Sulfides - Sulfosalts

(3.7)where z/y = 2 - (A+)i (A++)j [By Cz], A=metals, B=semi-metals, C=non-metals

(3.7.3)Dana Group

3.7.3.1 Smithite AgAsS2 A2/a 2/m

3.7.3.2 Miargyrite AgSbS2 C 2/c 2/m

Strunz Class:

II/E.08-20 II - Sulfides and sulphosalts

II/E - Sulfosalts (S : As,Sb,Bi = x) Sulfosalts with predominant Silver, x = 6.0 - 1.6

II/E.08 - Treshmannite - Dervillite series

II/E.08-10 Trechmannite AgAsS2 R 3m 3 2/m

II/E.08-20 Smithite AgAsS2 A2/a 2/m

II/E.08-30 Dervillite Ag2AsS2 P 2/a 2/m

Other Smithite Information

References:

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

See Also:

Links to other databases for Smithite :
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 - WWW-MINCRYST 13 -École des Mines de Paris

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

Smithite

AgAsS2
Dana No: 3.7.3.1 Strunz No: II/E.08-20
Locality:

Notes: