Semseyite Mineral Data

Semseyite Mineral Data +

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General Semseyite Information

Chemical Formula:

Pb9Sb8S21

Composition:

Molecular Weight = 3,512.19 gm

Antimony 27.73 % Sb

Lead 53.10 % Pb

Sulfur 19.17 % S

______

100.00 %

Empirical Formula:

Pb₉Sb₈S₂₁

Environment:

In hydrothermal veins formed at moderate temperature.

IMA Status:

Valid Species (Pre-IMA) 1881

Locality:

Felsobanya (Baia Sprie), Rumania. Link to MinDat.org Location Data.

Name Origin:

For Andor von Semsey (1833-1923), a Hungarian nobleman, who was also an amateur mineralogist.

Synonym:

ICSD 38838

PDF 22-1130

Semseyite Image

Images:

Semseyite

Comments: Crystal clusters of semseyite crystals to 1 cm on sphalerite.
Location: Herja, Romania. Scale: Picture size 5 cm.
© John Veevaert

Images:

Semseyite

Comments: Tabular crystals forming groups and rosettes of gray semseyite with creamy greenish yellow siderite.
Location: Herja mine, Maramures Rumania. Scale: 6.5 x 6 x 3.5 cm.
© Fabre Minerals

Semseyite Crystallography

Axial Ratios:

a:b:c =1.1356:1:2.0623

Cell Dimensions:

a = 13.48, b = 11.87, c = 24.48, Z = 4; beta = 105.75° V = 3,769.92 Den(Calc)= 6.19

Crystal System:

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

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

By Intensity(I/I_o): 3.26(1), 2.95(0.9), 3.81(0.9),

Forms:

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Forms: [ 0 1 0] [ 1 1 0] [ 1 0 0] [ 0 0 1]

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Physical Properties of Semseyite

Cleavage:

[112] Good

Color:

Black, Gray.

Density:

5.8 - 6.1, Average = 5.94

Diaphaniety:

Opaque

Fracture:

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

Habit:

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

Habit:

Spherical - Spherical, rounded aggregates.

Habit:

Tabular - Form dimensions are thin in one direction.

Hardness:

2.5 - Finger Nail

Luster:

Metallic

Streak:

black

Optical Properties of Semseyite

Optical Data:

NCalc= 1.47 - from Gladstone-Dale relationship (KC = 0.0761) where Ncalc=Dcalc*KC+1
NCalc= 1.45 - from Gladstone-Dale relationship (KC = 0.0761) where Ncalc=Dmeas*KC+1

RL Anisotrophism:

Strong.

RL Color:

White with light green tint.

RL Pleochroism:

Very weak, in yellow green to darker, grayish green.

Reflectivity

**Standardized Intensity (100%) Reflection Spectra of Semseyite in Air**
λ	R₁	R₂	∑ R₁(λ)	∑ R₂(λ)
400 nm	39.20	47.70
420 nm	38.30	46.60
440 nm	37.40	45.50
460 nm	36.90	44.80
480 nm	36.50	44.20
500 nm	36.30	43.80
520 nm	36.10	43.60
540 nm	36.00	43.30
560 nm	35.80	42.90
580 nm	35.30	42.30
600 nm	34.80	41.60
620 nm	34.10	40.70
640 nm	33.40	39.80
660 nm	32.50	38.70
680 nm	31.50	37.60
700 nm	30.50	36.80

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

Calculated Properties of Semseyite

Electron Density:

r_electron=5.22 gm/cc
note: r_Semseyite=6.19 gm/cc.

Fermion Index

Fermion Index = 0.11877
Boson Index = 0.88123

Photoelectric:

PE_Semseyite=1,063.61 barns/electron
U=PE_Semseyite x r_electron=5,556.15 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Semseyite is Not Radioactive

Semseyite Classification

Dana Class:

3.6.20.4 (3)Sulfides - Sulfosalts

(3.6)where 2 < z/y < 2.49 - (A+)i (A++)j [By Cz], A=metals, B=semi-metals, C=non-metals

(3.6.20)Fuloppite Group (Monoclinc: C2/c containing Pb, Sb)

3.6.20.1 Fuloppite Pb3Sb8S15 C 2/c 2/m

3.6.20.2 Plagionite Pb5Sb8S17 C 2/c 2/m

3.6.20.3 Heteromorphite Pb7Sb8S19 C 2/c 2/m

3.6.20.4 Semseyite Pb9Sb8S21 C 2/c 2/m

3.6.20.5 Rayite (Ag,Tl)2Pb8Sb8S21 C 2/c 2/m

Strunz Class:

II/E.21-20 II - Sulfides and sulphosalts

II/E - Sulfosalts (S : As,Sb,Bi = x), Sulfosalts with predominant Iron and Copper x = 2.0

II/E.21 - Rayite - Fülöppite series

II/E.21-10 Rayite (Ag,Tl)2Pb8Sb8S21 C 2/c 2/m

II/E.21-20 Semseyite Pb9Sb8S21 C 2/c 2/m

II/E.21-30 Heteromorphite Pb7Sb8S19 C 2/c 2/m

II/E.21-40 Plagionite Pb5Sb8S17 C 2/c 2/m

II/E.21-50 Fuloppite Pb3Sb8S15 C 2/c 2/m

Other Semseyite Information

References:

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

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

Semseyite

Pb9Sb8S21
Dana No: 3.6.20.4 Strunz No: II/E.21-20
Locality:

Notes: