Alacranite Mineral Data

Alacranite Mineral Data +

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General Alacranite Information

Chemical Formula:

As8S9

Composition:

Molecular Weight = 887.97 gm

Arsenic 67.50 % As

Sulfur 32.50 % S

______

100.00 %

Empirical Formula:

As₈S₉

Environment:

Occurs as a cement in a sandy gravel (Uson caldera, USSR); in hydrothermal As-S veins (Alacran deposit, Chile).

IMA Status:

Approved IMA 1986

Locality:

In the Uson caldera, Kamchatka, USSR. From the Alacran deposit, Pampa Larga, Chile. Link to MinDat.org Location Data.

Name Origin:

For the occurrence in the Alacran deposit, Chile.

Synonym:

ICSD 42387

PDF 42-537

Alacranite Image

Images:

Alacranite

Comments: Red crystals of alacranite.
Location: Mine Wilmsdorfer Schacht, Possendorf near Dresden, Sachsen, Germany. Scale: Picture size 4 mm.
© Thomas Witzke / Abraxas-Verlag

Alacranite Crystallography

Axial Ratios:

a:b:c =1.0355:1:0.9559

Cell Dimensions:

a = 9.942, b = 9.601, c = 9.178, Z = 2; beta = 101.94° V = 857.12 Den(Calc)= 3.44

Crystal System:

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

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

By Intensity(I/I_o): 2.9319(1)(222), 5.8638(0.89)(111), 3.0493(0.87)(221),5.0927(0.71)(111), 3.2791(0.69)(022), 3.0719(0.68)(310), 4.0307(0.58)(112),

Crystal Structure:

Mouse
drag1 - LMB Manipulate Structure
drag2 - RMB Resize/Rotate
Keyboard
S - Stereo Pair on/off
H - Help Screen
I - Data Info
A - Atoms On/Off
P - Polyhedra On/Off
B - Bonds On/Off
Help on Above

Bonazzi P , Bindi L , Popova V , Pratesi G , Menchetti S , American Mineralogist , 88 (2003) p.1796-1800, Alacranite, As8S9: structural study of the holotype and re-assignment, of the original chemical formula

View Additional jPOWD Structure files for Alacranite
[1]

Physical Properties of Alacranite

Cleavage:

[???] Indistinct

Color:

Red, Orange yellow.

Density:

3.4 - 3.46, Average = 3.43

Diaphaniety:

Transparent

Habit:

Equant Grains - Granular material with equel dimensions in x, y, and z.

Habit:

Euhedral Crystals - Occurs as well-formed crystals showing good external form.

Hardness:

1.5 - Between Talc and Gypsum

Luster:

Adamantine - Greasy

Streak:

orange

Optical Properties of Alacranite

Optical Data:

Biaxial (+), a=2.39, g=2.52, bire=0.1300

Pleochroism (x):

orange yellow.

Pleochroism (y):

orange yellow.

Pleochroism (z):

orange yellow.

RL Color:

Light gray with rose-yellow internal reflections.

Reflectivity

**Standardized Intensity (100%) Reflection Spectra of Alacranite in Air**
λ	R₁	R₂	∑ R₁(λ)	∑ R₂(λ)
400 nm	13.00	14.00
425 nm	13.20	14.60
450 nm	13.30	14.80
475 nm	13.40	14.80
500 nm	13.30	14.50
525 nm	13.10	14.30
550 nm	13.20	14.50
575 nm	13.40	14.70
600 nm	13.50	14.80
625 nm	13.60	14.90
650 nm	13.70	15.00
675 nm	13.80	15.00
700 nm	13.90	15.10

**Calculated Relative Intensity Colors of Alacranite in Air**
Relative Intensity	0%	70%	100%	140%	210%	280%	350%	420%	490%	560%	630%	670%
R₁
R₂

Calculated Properties of Alacranite

Electron Density:

r_electron=3.16 gm/cc
note: r_Alacranite=3.44 gm/cc.

Fermion Index

Fermion Index = 0.00243
Boson Index = 0.99757

Photoelectric:

PE_Alacranite= 49.28 barns/electron
U=PE_Alacranite x r_electron= 155.79 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Alacranite is Not Radioactive

Alacranite Classification

Dana Class:

2.8.22.4 (2)Sulfides - Including Selenides and Tellurides

(2.8)where Am Bn Xp, with (m+n):p=1:1

(2.8.22)Dana Group

2.8.22.1 Realgar AsS P 2₁/n 2/m

2.8.22.2 Pararealgar AsS P 2₁/c 2/m

2.8.22.3 Uzonite As4S5 P 2₁/m 2/m

2.8.22.4 Alacranite As8S9 P 2/c 2/m

Strunz Class:

II/F.02-50 II - Sulfides and sulphosalts

II/F - Sulfides with nonmetallic properties, Arsenic-Sulfides

II/F.02 - Duranusite - Jeromite series

II/F.02-10 Duranusite As4S Unk Ortho

II/F.02-20 Dimorphite As4S3 P nma 2/m 2/m 2/m

II/F.02-30 Realgar AsS P 2₁/n 2/m

II/F.02-40 Pararealgar AsS P 2₁/c 2/m

II/F.02-50 Alacranite As8S9 P 2/c 2/m

II/F.02-60 Uzonite As4S5 P 2₁/m 2/m

II/F.02-70 Orpiment As2S3 P 2₁/n 2/m

II/F.02-80 Laphamite As2(Se,S)3 P 2₁/n 2/m

II/F.02-90 Jeromite As(S,Se)2 None

Other Alacranite Information

References:

NAME( AntBidBlaNic1) PHYS. PROP.(Am.Min.,v.73, p189, v 87, p 357, v 88, p 1796) OPTIC PROP.(Am.Min.,Vol.73,p189,1988, AntBidBlaNic1)

See Also:

Links to other databases for Alacranite :
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 -École des Mines de Paris

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Alacranite

As8S9
Dana No: 2.8.22.4 Strunz No: II/F.02-50
Locality:

Notes: