Melanarsite
A valid IMA mineral species
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About Melanarsite
Formula:
K3Cu7Fe3+O4(AsO4)4
Colour:
Black
Lustre:
Vitreous
Hardness:
4
Specific Gravity:
4.39 (Calculated)
Crystal System:
Monoclinic
Name:
The name reflects belonging of the mineral to arsenates and its black colour (colour name taken from Greek)
New structure type: heteropolyhedral pseudo-framework comprises distorted Cu(1-3)O6 and (Fe,Cu)O6 octahedra, and As(1-3)O4 tetrahedra. There are tunnels and voids occupied by two independent K atoms ([8]K & [7]K).
Melanarsite is the second K-Cu-Fe-As mineral after obradovicite-KCu.
Melanarsite is the second K-Cu-Fe-As mineral after obradovicite-KCu.
Unique Identifiers
Mindat ID:
46427
Long-form identifier:
mindat:1:1:46427:7
IMA Classification of Melanarsite
Approved
IMA Formula:
K3Cu2+7Fe3+O4(As5+O4)4
Approval year:
2014
First published:
2016
Type description reference:
Pekov, Igor V., Zubkova, Natalia V., Yapaskurt, Vasiliy O., Polekhovsky, Yury S., Vigasina, Marina F., Belakovskiy, Dmitry I., Britvin, Sergey N., Sidorov, Evgeny G., Pushcharovsky, Dmitry Y. (2016) New arsenate minerals from the Arsenatnaya fumarole, Tolbachik volcano, Kamchatka, Russia. VI. Melanarsite, K3Cu7Fe3+O4(AsO4)4. Mineralogical Magazine, 80 (5) 855-867 doi:10.1180/minmag.2016.080.027
Classification of Melanarsite
8.BH.75
8 : PHOSPHATES, ARSENATES, VANADATES
B : Phosphates, etc., with additional anions, without H2O
H : With medium-sized and large cations, (OH,etc.):RO4 = 1:1
8 : PHOSPHATES, ARSENATES, VANADATES
B : Phosphates, etc., with additional anions, without H2O
H : With medium-sized and large cations, (OH,etc.):RO4 = 1:1
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 |
|---|---|---|
| Mea | 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 Melanarsite
Vitreous
Transparency:
Opaque
Colour:
Black
Streak:
Dark green with an olive hue
Hardness:
4 on Mohs scale
Hardness:
VHN100=203 - Vickers
Tenacity:
Brittle
Cleavage:
None Observed
Fracture:
Irregular/Uneven
Density:
4.39 g/cm3 (Calculated)
Optical Data of Melanarsite
Type:
Biaxial
RI values:
nα = 1.80(1) nγ = 1.91(1)
Max. Birefringence:
δ = 0.110
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:
Moderate
Anisotropism:
Very weak
Bireflectance:
Weak
Reflectivity:
| Wavelength | R1 (%) | R2 (%) |
|---|---|---|
| 400nm | 11.4% | 10.2% |
| 420nm | 11.1% | 9.9% |
| 440nm | 10.9% | 9.7% |
| 460nm | 10.6% | 9.4% |
| 470nm | 10.5% | 9.4% |
| 480nm | 10.4% | 9.3% |
| 500nm | 10.2% | 9.1% |
| 520nm | 10.1% | 9.0% |
| 540nm | 10.0% | 8.9% |
| 546nm | 10.0% | 8.9% |
| 560nm | 9.9% | 8.8% |
| 580nm | 9.8% | 8.7% |
| 589nm | 9.7% | 8.7% |
| 600nm | 9.7% | 8.7% |
| 620nm | 9.6% | 8.6% |
| 640nm | 9.5% | 8.6% |
| 650nm | 9.5% | 8.6% |
| 660nm | 9.4% | 8.5% |
| 680nm | 9.4% | 8.4% |
| 700nm | 9.3% | 8.4% |
Graph shows reflectance levels at different wavelengths (in nm). Peak reflectance is 11.4%.
R1 shown in black, R2 shown in red
Colour in reflected light:
Dark grey
Pleochroism:
Weak
Comments:
Observed in the thinnest particles, is strong with Z (very dark greyish-green) > X (green to pale green).
Comments:
Optical sign, β, and 2V not determined.
Chemistry of Melanarsite
Mindat Formula:
K3Cu7Fe3+O4(AsO4)4
Element Weights:
Common Impurities:
Zn
Crystallography of Melanarsite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/b
Setting:
C2/c
Cell Parameters:
a = 11.4763(9) Å, b = 16.620(2) Å, c = 10.1322(8) Å
β = 105.078(9)°
β = 105.078(9)°
Ratio:
a:b:c = 0.691 : 1 : 0.61
Unit Cell V:
1,866.04 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Tabular to prismatic crystals up to 0.4 mm; clusters; forming crust
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 9.22 Å | (100) |
| 7.59 Å | (35) |
| 6.084 Å | (17) |
| 4.595 Å | (26) |
| 3.124 Å | (22) |
| 2.763 Å | (20) |
| 2.570 Å | (23) |
| 2.473 Å | (16) |
Reference:
Pekov, Igor V., Zubkova, Natalia V., Yapaskurt, Vasiliy O., Polekhovsky, Yury S., Vigasina, Marina F., Belakovskiy, Dmitry I., Britvin, Sergey N., Sidorov, Evgeny G., Pushcharovsky, Dmitry Y. (2016) New arsenate minerals from the Arsenatnaya fumarole, Tolbachik volcano, Kamchatka, Russia. VI. Melanarsite, K3Cu7Fe3+O4(AsO4)4. Mineralogical Magazine, 80 (5) 855-867 doi:10.1180/minmag.2016.080.027
Comments:
From Type Description.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 45a : [Sulfates, arsenates, selenates, antimonates] |
Type Occurrence of Melanarsite
General Appearance of Type Material:
Tabular to prismatic crystals up to 0.4 mm, separate or combined in clusters up to 1 mm across or in interrupted crusts up to 0.02 x 1 x 1 cm covering basalt scoria.
Place of Conservation of Type Material:
Type material is deposited in the collections of the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia, registration number 4550/1
Geological Setting of Type Material:
Fumaroles
Associated Minerals at Type Locality:
Reference:
Pekov, Igor V., Zubkova, Natalia V., Yapaskurt, Vasiliy O., Polekhovsky, Yury S., Vigasina, Marina F., Belakovskiy, Dmitry I., Britvin, Sergey N., Sidorov, Evgeny G., Pushcharovsky, Dmitry Y. (2016) New arsenate minerals from the Arsenatnaya fumarole, Tolbachik volcano, Kamchatka, Russia. VI. Melanarsite, K3Cu7Fe3+O4(AsO4)4. Mineralogical Magazine, 80 (5) 855-867 doi:10.1180/minmag.2016.080.027
Synonyms of Melanarsite
Other Language Names for Melanarsite
Dutch:Melanarsiet
German:Melanarsit
Related Minerals - Strunz-mindat Grouping
| 8.BH. | Peterchinite | Zn3Zn2(OH)6As[O3(OH)3] |
| 8.BH. | Reznitskyite | CaMg(VO4)F |
| 8.BH. | Plumbogottlobite | PbMg(VO4)(OH) |
| 8.BH. | Cuprozheshengite | Pb4CuZn2(AsO4)2(PO4)2(OH)2 |
| 8.BH. | Zheshengite | Pb4ZnZn2(AsO4)2(PO4)2(OH)2 |
| 8.BH. | Crimsonite | PbFe3+2(PO4)2(OH)2 |
| 8.BH.05 | Thadeuite | Ca(Mg,Fe2+)3(PO4)2(OH,F)2 |
| 8.BH.10 | Panasqueiraite | CaMg(PO4)(OH) |
| 8.BH.10 | Isokite | CaMg(PO4)F |
| 8.BH.10 | Lacroixite | NaAl(PO4)F |
| 8.BH.10 | Arsenatrotitanite | NaTi(AsO4)O |
| 8.BH.10 | Maxwellite | NaFe3+(AsO4)F |
| 8.BH.10 | Durangite | NaAl(AsO4)F |
| 8.BH.10 | Kononovite | NaMg(SO4)F |
| 8.BH.15 | Drugmanite | Pb2Fe3+(PO4)(PO3OH)(OH)2 |
| 8.BH.20 | Nigelcookite | PbFe2+2V3+2(PO4)3(OH)3 |
| 8.BH.20 | Plumbojohntomaite | PbFe2+2Fe3+2(PO4)3(OH)3 |
| 8.BH.20 | Cirrolite | Ca3Al2(PO4)3(OH)3 (?) |
| 8.BH.20 | Penikisite | Ba(Mg,Fe2+,Ca)2Al2(PO4)3(OH)3 |
| 8.BH.20 | Perloffite | Ba(Mn2+,Fe2+)2Fe3+2(PO4)3(OH)3 |
| 8.BH.20 | Bjarebyite Group | |
| 8.BH.20 | Strontioperloffite | SrMn2+2Fe3+2(PO4)3(OH)3 |
| 8.BH.20 | Plumboperloffite | PbMn2+2Fe3+2(PO4)3(OH)3 |
| 8.BH.20 | Johntomaite | BaFe2+2Fe3+2(PO4)3(OH)3 |
| 8.BH.20 | Bjarebyite | (Ba,Sr)(Mn2+,Fe2+,Mg)2Al2(PO4)3(OH)3 |
| 8.BH.20 | Kulanite | Ba(Fe2+,Mn2+,Mg)2(Al,Fe3+)2(PO4)3(OH)3 |
| 8.BH.25 | Bertossaite | Li2CaAl4(PO4)4(OH)4 |
| 8.BH.25 | Natropalermoite | Na2SrAl4(PO4)4(OH)4 |
| 8.BH.25 | Palermoite | Li2SrAl4(PO4)4(OH)4 |
| 8.BH.30 | Sewardite | CaFe3+2(AsO4)2(OH)2 |
| 8.BH.30 | Carminite | PbFe3+2(AsO4)2(OH)2 |
| 8.BH.35 | Adelite | CaMg(AsO4)(OH) |
| 8.BH.35 | Duftite | PbCu(AsO4)(OH) |
| 8.BH.35 | Cobaltaustinite | CaCo(AsO4)(OH) |
| 8.BH.35 | Nickelaustinite | CaNi(AsO4)(OH) |
| 8.BH.35 | Gabrielsonite | PbFe3+(As3+O3)O |
| 8.BH.35 | Conichalcite | CaCu(AsO4)(OH) |
| 8.BH.35 | Arsendescloizite | PbZn(AsO4)(OH) |
| 8.BH.35 | 'Duftite-alpha' | PbCu(AsO4)(OH) |
| 8.BH.35 | Gottlobite | CaMg(VO4)(OH) |
| 8.BH.35 | Austinite | CaZn(AsO4)(OH) |
| 8.BH.35 | Hermannroseite | CaCu(PO4)(OH) |
| 8.BH.35 | Tangeite | CaCu(VO4)(OH) |
| 8.BH.40 | Čechite | PbFe2+(VO4)(OH) |
| 8.BH.40 | Khorixasite | (Bi0.67◻0.33)Cu(VO4)(OH) |
| 8.BH.40 | Mottramite | PbCu(VO4)(OH) |
| 8.BH.40 | Descloizite | PbZn(VO4)(OH) |
| 8.BH.40 | Pyrobelonite | PbMn2+(VO4)(OH) |
| 8.BH.45 | Bayldonite | PbCu3(AsO4)2(OH)2 |
| 8.BH.45 | Vésigniéite | BaCu3(VO4)2(OH)2 |
| 8.BH.50 | Paganoite | NiBi(AsO4)O |
| 8.BH.55 | Jagowerite | BaAl2(PO4)2(OH)2 |
| 8.BH.55 | Harrisonite | Ca(Fe2+,Mg)6(PO4)2(SiO4)2 |
| 8.BH.60 | Attakolite | CaMn2+Al4(SiO3OH)(PO4)3(OH)4 |
| 8.BH.65 | Leningradite | PbCu3(VO4)2Cl |
| 8.BH.70 | Katiarsite | KTiO(AsO4) |
| 8.BH.70 | Yurgensonite | K2SnTiO2(AsO4)2 |
| 8.BH.80 | Evseevite | Na2Mg(AsO4)F |
| 8.BH.80 | Moraskoite | Na2Mg(PO4)F |
| 8.BH.85 | Piccoliite | NaCaMn3+2(AsO4)2O(OH) |
Radioactivity
Radioactivity:
| Element | % Content | Activity (Bq/kg) | Radiation Type |
|---|---|---|---|
| Uranium (U) | 0.0000% | 0 | α, β, γ |
| Thorium (Th) | 0.0000% | 0 | α, β, γ |
| Potassium (K) | 9.4773% | 2,938 | β, γ |
For comparison:
- Banana: ~15 Bq per fruit
- Granite: 1,000–3,000 Bq/kg
- EU exemption limit: 10,000 Bq/kg
Note: Risk is shown relative to daily recommended maximum exposure to non-background radiation of 1000 µSv/year. Note that natural background radiation averages around 2400 µSv/year so in reality these risks are probably extremely overstated! With infrequent handling and safe storage natural radioactive minerals do not usually pose much risk.
Interactive Simulator:
Note: The mass selector refers to the mass of radioactive mineral present, not the full specimen, also be aware that the matrix may also be radioactive, possibly more radioactive than this mineral!
Activity: –
| Distance | Dose rate | Risk |
|---|---|---|
| 1 cm | ||
| 10 cm | ||
| 1 m |
The external dose rate (D) from a radioactive mineral is estimated by summing the gamma radiation contributions from its Uranium, Thorium, and Potassium content, disregarding daughter-product which may have a significant effect in some cases (eg 'pitchblende'). This involves multiplying the activity (A, in Bq) of each element by its specific gamma ray constant (Γ), which accounts for its unique gamma emissions. The total unshielded dose at 1 cm is then scaled by the square of the distance (r, in cm) and multiplied by a shielding factor (μshield). This calculation provides a 'worst-case' or 'maximum risk' estimate because it assumes the sample is a point source and entirely neglects any self-shielding where radiation is absorbed within the mineral itself, meaning actual doses will typically be lower. The resulting dose rate (D) is expressed in microsieverts per hour (μSv/h).
D = ((AU × ΓU) + (ATh × ΓTh) + (AK × ΓK)) / r2 × μshield
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 Melanarsite
mindat.org URL:
https://www.mindat.org/min-46427.html
Please feel free to link to this page.
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References for Melanarsite
Reference List:
Williams, P. A., Hatert, F., Pasero, M., Mills, S. J. (2014) IMA Commission on New Minerals, Nomenclature and Classification (CNMNC), CNMNC Newsletter No. 22. Mineralogical Magazine, 78 (5) 1241-1248 doi:10.1180/minmag.2014.078.5.10
Pekov, Igor V., Zubkova, Natalia V., Yapaskurt, Vasiliy O., Polekhovsky, Yury S., Vigasina, Marina F., Belakovskiy, Dmitry I., Britvin, Sergey N., Sidorov, Evgeny G., Pushcharovsky, Dmitry Y. (2016) New arsenate minerals from the Arsenatnaya fumarole, Tolbachik volcano, Kamchatka, Russia. VI. Melanarsite, K3Cu7Fe3+O4(AsO4)4. Mineralogical Magazine, 80 (5) 855-867 doi:10.1180/minmag.2016.080.027
Localities for Melanarsite
Showing 1 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.
Russia (TL) | |
| Pekov et al. (2016) |
Quick NavTopAbout MelanarsiteUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography X-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesStrunz-MindatRadioactivityOther InformationInternet Links References Localities Locality List
Arsenatnaya fumarole, Second scoria cone, Northern Breakthrough, Great Fissure eruption, Tolbachik Volcanic field, Milkovsky District, Kamchatka Krai, Russia