Alacránite
A valid IMA mineral species
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About Alacránite
Formula:
As8S9
Colour:
Orange to pale gray with rose-yellow internal reflections
Lustre:
Vitreous, Resinous, Greasy
Hardness:
1½
Specific Gravity:
3.43
Crystal System:
Monoclinic
Name:
Named after its discovery locality in Chile.
Different from (unnamed) natural beta-As4S4.
Name Encoding
ASCII-7:
Alacranite
Unique Identifiers
Mindat ID:
91
Long-form identifier:
mindat:1:1:91:4
IMA Classification of Alacránite
Approved
Approval year:
1985
First published:
1986
Classification of Alacránite
2.FA.20
2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
F : Sulfides of arsenic, alkalies; sulfides with halide, oxide, hydroxide, H2O
A : With As, (Sb), S
2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
F : Sulfides of arsenic, alkalies; sulfides with halide, oxide, hydroxide, H2O
A : With As, (Sb), S
2.8.22.
2 : SULFIDES
8 : AmXp, with m:p = 1:1
2 : SULFIDES
8 : AmXp, with m:p = 1:1
3.7.6
3 : Sulphides, Selenides, Tellurides, Arsenides and Bismuthides (except the arsenides, antimonides and bismuthides of Cu, Ag and Au, which are included in Section 1)
7 : Sulphides etc. of V, As, Sb and Bi
3 : Sulphides, Selenides, Tellurides, Arsenides and Bismuthides (except the arsenides, antimonides and bismuthides of Cu, Ag and Au, which are included in Section 1)
7 : Sulphides etc. of V, As, Sb and Bi
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Acr | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Alacránite
Vitreous, Resinous, Greasy
Transparency:
Translucent
Colour:
Orange to pale gray with rose-yellow internal reflections
Comment:
yellow-orange in transmitted light
Streak:
Yellow-orange
Hardness:
1½ on Mohs scale
Hardness:
VHN20=69 kg/mm2 - Vickers
Tenacity:
Very brittle
Cleavage:
Imperfect/Fair
imperfect on {100}
imperfect on {100}
Fracture:
Conchoidal
Density:
3.43(3) g/cm3 (Measured) 3.43 g/cm3 (Calculated)
Optical Data of Alacránite
Type:
Biaxial (+)
RI values:
nα = 2.39(1) nγ = 2.52(2)
Max. Birefringence:
δ = 0.130
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
Very High (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
No measured or calculated 2V is on file for this mineral, so the value used here (92°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
No measured or calculated 2V is on file for this mineral, so the value used here (92°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.
Dispersion:
r < v
Reflectivity:
| Wavelength | R1 (%) | R2 (%) |
|---|---|---|
| 400nm | 13.0% | 14.0% |
| 425nm | 13.2% | 14.6% |
| 450nm | 13.3% | 14.8% |
| 475nm | 13.4% | 14.8% |
| 500nm | 13.3% | 14.5% |
| 525nm | 13.1% | 14.3% |
| 550nm | 13.2% | 14.5% |
| 575nm | 13.4% | 14.7% |
| 600nm | 13.5% | 14.8% |
| 625nm | 13.6% | 14.9% |
| 650nm | 13.7% | 15.0% |
| 675nm | 13.8% | 15.0% |
| 700nm | 13.9% | 15.1% |
Graph shows reflectance levels at different wavelengths (in nm). Peak reflectance is 15.1%.
R1 shown in black, R2 shown in red
Colour in reflected light:
Light gray
Internal Reflections:
Rose-yellow
Chemistry of Alacránite
Mindat Formula:
As8S9
Elements listed:
Crystallography of Alacránite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P2/b
Setting:
P2/c
Cell Parameters:
a = 9.942 Å, b = 9.601 Å, c = 9.178 Å
β = 101.94°
β = 101.94°
Ratio:
a:b:c = 1.036 : 1 : 0.956
Unit Cell V:
857.1 ų
Z:
2
Morphology:
Crystals are pinacoidal, prismatic, and flattened on [100] , striated parallel [001] on {100} , other faces dull or tarnished, to 1 mm; as subhedral flattened and prismatic grains.
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 6.89 Å | (40) |
| 5.91 Å | (90) |
| 5.11 Å | (80) |
| 4.05 Å | (70) |
| 3.291 Å | (50) |
| 3.064 Å | (100) |
| 2.950 Å | (90) |
Comments:
Uzon caldera, Kamchatka, Russia (ICDD 42-537).
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 3a: Earth’s earliest Hadean crust | >4.50 |
| 11 : Volcanic fumarole minerals; reduced phases (see also #45) | |
| Stage 3b: Earth’s earliest hydrosphere | >4.45 |
| 12 : Hadean hydrothermal subsurface sulfide deposits (see also #33) | |
| High-? alteration and/or metamorphism | |
| 33 : Minerals deposited by hydrothermal metal-rich fluids (see also [#12]) | |
| Stage 10a: Neoproterozoic oxygenation/terrestrial biosphere | <0.6 |
| 50 : Coal and/or oil shale minerals | <0.36 |
| Stage 10b: Anthropogenic minerals | <10 Ka |
| 54 : Coal and other mine fire minerals (see also #51 and #56) |
Geological Setting:
in the condensation zone of a hydrothermal Hg–Sb–As system as cement in a sandy gravel (Uzon caldera, Russia); formed
at low temperatures in a polymetallic hydrothermal deposit on a submarine seamount (Conical Seamount, Papua New Guinea).
at low temperatures in a polymetallic hydrothermal deposit on a submarine seamount (Conical Seamount, Papua New Guinea).
Type Occurrence of Alacránite
Co-Type Localities:
Place of Conservation of Type Material:
Il’menskii Preserve Museum, Miass; A.E. Fersman Mineralogical Museum, Academy of Sciences, Moscow, Russia.
Geological Setting of Type Material:
In hydrothermal As–S veins
Associated Minerals at Type Locality:
Synonyms of Alacránite
Other Language Names for Alacránite
Dutch:Alacrániet
French:Alacránite
German:Alacranit
Norwegian:Alacránitt
Russian:Алакранит
Spanish:Alacranita
Relationship of Alacránite to other Species
Forms a series with:
Common Associates
Associations Based on Photo Data:
Related Minerals - Strunz-mindat Grouping
| 2.FA. | Bonazziite | As4S4 |
| 2.FA. | Anorpiment | As2S3 |
| 2.FA. | Paradimorphite | As4S3 |
| 2.FA.05 | Duranusite | As4S |
| 2.FA.10 | Dimorphite | As4S3 |
| 2.FA.15b | Pararealgar | As4S4 |
| 2.FA.15a | Realgar | As4S4 |
| 2.FA.15d | 'UM1970-18-S:As' | As4S4 |
| 2.FA.25 | Uzonite | As4S5 |
| 2.FA.30 | Laphamite | As2Se3 |
| 2.FA.30 | Orpiment | As2S3 |
| 2.FA.35 | Getchellite | AsSbS3 |
| 2.FA.40 | Wakabayashilite | [(As,Sb)6S9][As4S5] |
| 2.FA.40 | Kalgoorlieite | As2Te3 |
Other Information
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Alacránite
mindat.org URL:
https://www.mindat.org/min-91.html
Please feel free to link to this page.
Please feel free to link to this page.
Search Engines:
External Links:
Mineral Dealers:
References for Alacránite
Reference List:
Clark, Alan H. (1970) Alpha-arsenic sulfide, from Mina Alacrán, Pampa Larga, Chile. American Mineralogist, 55 (7-8) 1338-1344 [as unnamed "AsS" modification]
Hawthorne, Frank C., Burke, Ernst A. J., Ercit, T. Scott, Grew, Edward S., Grice, Joel D., Jambor, John L., Puziewicz, Jacek, Roberts, Andrew C., Vanko, David A. (1988) New Mineral Names. American Mineralogist, 73 (1-2) 189-199
Burns, P. C., Percival, J. B. (2001) Alacranite, As4S4: a new occurrence, new formula, and determination of the crystal structure. The Canadian Mineralogist, 39 (3) 809-818 doi:10.2113/gscanmin.39.3.809
Bonazzi, Paola, Bindi, Luca, Popova, Valentina, Pratesi, Giovanni, Menchetti, Silvio (2003) Alacranite, As8S9: structural study of the holotype and re-assignment of the original chemical formula. American Mineralogist, 88 (11) 1796-1800 doi:10.2138/am-2003-11-1220
Burke, Ernst A. J. (2008) Tidying up mineral names: an IMA-CNMNC scheme for suffixes, hyphens and diacritical marks. The Mineralogical Record, 39 (2) 131-135
Bonazzi, Paola, Bindi, Luca (2008) A crystallographic review of arsenic sulfides: effects of chemical variations and changes induced by exposure to light. Zeitschrift für Kristallographie - Crystalline Materials, 223 (1). 132-147 doi:10.1524/zkri.2008.0011
Banaru, D. A., Aksenov, S. M., Yamnova, N. A., Banaru, A. M. (2023) Structural Complexity of Molecular, Chain, and Layered Crystal Structures of Natural and Synthetic Arsenic Sulfides. Crystallography Reports, 68 (2). 223-236 doi:10.1134/s1063774523020037
Bindi, Luca, Bonazzi, Paola, Chelazzi, Laura, Franceschini, Matteo M. N., Lepore, Giovanni O., Morana, Marta, Pratesi, Giovanni, Taddei, Alice, Zoppi, Matteo, Menchetti, Silvio (2024) Evidence of the existence of the As4S6 molecule produced by light exposure of alacranite, As8S9. European Journal of Mineralogy, 36 (4). 615-622 doi:10.5194/ejm-36-615-2024
Localities for Alacránite
Showing 26 localities.
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
Austria | |
| Dr. Günter Grundmann collection |
Bulgaria | |
| Miadenova (2000) |
Chile (TL) | |
| Clark (1970) +4 other references |
Czech Republic | |
| Pauliš P. Mineralogické lokality ... |
| Žáček et al. (1998) |
| Scharm B. |
Germany | |
| Walenta (1992) |
| |
| |
| Walenta (1992) |
| Blaß et al. (1999) +1 other reference |
| Thalheim +1 other reference |
| |
| Witzke et al. (1998) |
Italy | |
| Russo et al. (2017) |
Japan | |
| The Mineral Species of Japan (5th ed) +1 other reference |
Kyrgyzstan | |
| Bindi et al. (2015) |
New Zealand | |
| Kerr et al. (2018) |
| Kerr et al. (2018) | |
Papua New Guinea | |
| Rod Martin Collection |
| Burns et al. (2001) +2 other references |
Romania | |
| Szakáll et al. (2006) +2 other references |
Russia (TL) | |
| Popova et al. (1986) +2 other references |
| Pekov (1998) | |
| Bortnikova et al. (2017) |
Tajikistan | |
| Karpenko et al. (2023) |
Quick NavTopAbout AlacrániteName EncodingUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography X-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesRelationshipsCommon AssociatesStrunz-MindatOther InformationInternet Links References Localities Locality List
Uzon Caldera, Kronotsky Reserve, Yelizovsky District, Kamchatka Krai, Russia