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Stillwaterite

A valid IMA mineral species
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06371360017271926763499.jpg
Stillwaterite

Stillwater Complex, Montana, USA
04020340017271926796081.jpg
Stillwaterite

Fedorovo-Pansky massif, Murmansk Oblast, Russia
06371360017271926763499.jpg
Stillwaterite

Stillwater Complex, Montana, USA
04020340017271926796081.jpg
Stillwaterite

Fedorovo-Pansky massif, Murmansk Oblast, Russia
00048400017271926848448.jpg
Stillwaterite

Stillwater Complex, Montana, USA
04020340017271926796081.jpg
Stillwaterite

Fedorovo-Pansky massif, Murmansk Oblast, Russia
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About StillwateriteHide

00550400017271926867205.jpg
Stillwater Mine

Stillwater Mine, Stillwater County, Montana, USA
Formula:
Pd8As3
Lustre:
Metallic
Hardness:
4½
Specific Gravity:
10.96 (Calculated)
Crystal System:
Trigonal
Name:
Named after its discovery locality.
Likely polymorphous with arsenopalladinite. One of several Pd arsenide minerals, chemically comparable to isomertieite, Unnamed (Pd Arsenide), etc.

Also compare with UM1993-02-AsTe:Pd.


Unique IdentifiersHide

Mindat ID:
3787
Long-form identifier:
mindat:1:1:3787:3

IMA Classification of StillwateriteHide

Classification of StillwateriteHide

Strunz-mindat (2026):
2.AC.10a

2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
A : Alloys
C : Alloys of metalloids with PGE
Dana 8th ed.:
2.16.4.1

2 : SULFIDES
16 : Miscellaneous
Hey's CIM Ref.:
3.12.25

3 : Sulphides, Selenides, Tellurides, Arsenides and Bismuthides (except the arsenides, antimonides and bismuthides of Cu, Ag and Au, which are included in Section 1)
12 : Sulphides etc. of the platinum metals

Mineral SymbolsHide

As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.

Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.

SymbolSourceReference for Standard
SlwIMA–CNMNCWarr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43
StwThe Canadian Mineralogist (2019)The Canadian Mineralogist (2019) The Canadian Mineralogist list of symbols for rock- and ore-forming minerals (December 30, 2019). download

Pronunciation of StillwateriteHide

Pronunciation:
PlayRecorded byCountry
Jolyon RalphUnited Kingdom

Physical Properties of StillwateriteHide

Lustre:
Metallic
Hardness:
4½ on Mohs scale
Hardness:
VHN50=384 kg/mm2 - Vickers
Density:
10.96 g/cm3 (Calculated)

Optical Data of StillwateriteHide

Anisotropism:
weak (air; dark gray to brownish gray), distinct (oil, brownish black with a blue to yellow-brown tinge)
Reflectivity:
WavelengthR1 (%)R2 (%)
470nm51.6%52.7%
546nm52.5%53.2%
589nm53.1%53.7%
650nm54.4%55.0%


Graph shows reflectance levels at different wavelengths (in nm). Peak reflectance is 55.0%.
R1 shown in black, R2 shown in red
Colour in reflected light:
pale creamy gray with faint pinkish tint

Chemistry of StillwateriteHide

Mindat Formula:
Pd8As3
Element Weights:
Element% weight
Pd79.114 %
As20.887 %

Calculated from ideal end-member formula.
Elements listed:
As, Pd - search for minerals with similar chemistry

Crystallography of StillwateriteHide

Crystal System:
Trigonal
Cell Parameters:
a = 7.42 Å, c = 10.31 Å
Ratio:
a:c = 1 : 1.389
Unit Cell V:
491.58 ų (Calculated from Unit Cell)
Z:
3
Twinning:
rare
Comment:
Space group is P3 or P-3; data for the synthetic analogue: a = 7.4261(4) Å, c = 10.3097(9) Å, V = 492.38(7) Å3

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
2.115 Å(100)
2.355 Å(80)
1.351 Å(50)
0.8858 Å(40)
2.700 Å(30)
1.991 Å(30)
2.521 Å(20)

Geological EnvironmentHide

Paragenetic Mode(s):
Paragenetic ModeEarliest Age (Ga)
High-? alteration and/or metamorphism
33 : Minerals deposited by hydrothermal metal-rich fluids (see also [#12])
Stage 4b: Highly evolved igneous rocks>3.0
37 : Layered igneous intrusions and related PGE minerals

Type Occurrence of StillwateriteHide

Co-Type Localities:
ⓘ Stillwater Complex, Montana, USA
ⓘ Stillwater Mine, Stillwater County, Montana, USA
General Appearance of Type Material:
Anhedral grains up to 265 µm.
Place of Conservation of Type Material:
Royal Ontario Museum, Toronto, Ontario, Canada (no. M33559).
The Natural History Museum, London, England (no. 1979,129).
National Museum of Natural History, Washington, D.C., USA (no. 132500).
Geological Setting of Type Material:
Layered ultramafic igneous complexes (Stillwater complex: Banded and Upper zones).
Associated Minerals at Type Locality:
BraggiteChalcopyriteDigeniteNative GoldHollingworthite
PalladoarsenidePentlanditePyrrhotiteSperrylite
Reference:
Cabri, L.J., Laflamme, J.H.G., Stewart, J.M., Rowland, J.F., Chen, T.T. (1975) New data on some palladium arsenides and antimonides. The Canadian Mineralogist: 13: 321-335.

Synonyms of StillwateriteHide

Other Language Names for StillwateriteHide

Related Minerals - Strunz-mindat GroupingHide

2.AC.VadlazarenkovitePd8Bi1.5Te1.25As0.25Trig. 3m(32/m) : R3c
2.AC.TörnroositePd11As2Te2Iso. m3m(4/m32/m) : Fd3m
2.AC.05bVincentitePd3AsMon.
2.AC.05aAtheneitePd2As0.75Hg0.25Hex. 6m2 : P62m
2.AC.10cArsenopalladinitePd8(As,Sb)3Tric. 1 : P1
2.AC.10bMertieitePd8Sb2.5As0.5Trig. 3m(32/m) : R3c
2.AC.15aIsomertieitePd11Sb2As2Iso. m3m(4/m32/m) : Fd3m
2.AC.15aMiessiitePd11Te2Se2Iso. m3m(4/m32/m) : Fd3m
2.AC.15bPseudomertieitePd11(Sb,As)4Hex.
2.AC.20cMenshikovitePd3Ni2As3Hex. 6/m : P63/m
2.AC.20aStibiopalladinitePd5Sb2Hex.
2.AC.20bPalarstanidePd5(Sn,As)2Hex.
2.AC.25cPalladodymite(Pd,Rh)2AsOrth. mmm(2/m2/m2/m) : Pnma
2.AC.25dNaldrettitePd2SbOrth. mm2 : Cmc21
2.AC.25bRhodarsenide(Rh,Pd)2AsOrth.
2.AC.25eMajakitePdNiAsHex.
2.AC.25aPalladoarsenidePd2AsMon. 2/m : P2/m
2.AC.25fPalladobismutharsenidePd2(As,Bi)Orth.
2.AC.30'UM1999-02-As:NiRh'(Rh,Ni)7As4
2.AC.30PolkanoviteRh12As7Hex. 6/m : P63/m
2.AC.35bUngavaitePd4Sb3Tet. 422 : P41212
2.AC.35aGenkinitePt4Sb3Tet. 422
2.AC.40PolaritePd(Bi,Pb)Orth. mm2 : Cmc21
2.AC.45aFrooditeα-PdBi2Mon. 2/m : B2/m
2.AC.50ViteitePd5InAsTet. 4/mmm(4/m2/m2/m) : P4/mmm
2.AC.50NipalarsiteNi8Pd3As4Iso. m3m(4/m32/m)

Other InformationHide

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 StillwateriteHide

References for StillwateriteHide

Localities for StillwateriteHide

Showing 39 localities.

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
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Locality ListHide

- 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). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).

All localities listed without proper references should be considered as questionable.
Canada
 
  • New Brunswick
    • Kings Co.
      • Cardwell Parish
Canadian Mineralogist 45 +1 other reference
  • Nunavut
    • Kivalliq Region
Campos-Alvarez et al. (2012)
  • Ontario
    • Thunder Bay District
      • Coldwell complex
McDonald et al. (2015) +1 other reference
Good et al. (2017)
      • Lac des Iles Area
Louis J. Cabri and J.H. Gilles Laflamme (1979) +2 other references
Watkinson et al. (1979) +1 other reference
      • Seeley Lake Area
Good et al. (2017)
EcoMetrix Reort for Stillwater Canada Inc (2012)
Good et al. (2017) +1 other reference
Finland
 
Törnroos et al. (1998)
    • Enontekiö
Kojonen et al. (2007) +2 other references
    • Inari
Kojonen et al. (2014)
    • Portimo complex
Iljina (1994)
Madagascar
 
  • Atsinanana
    • Toamasina II District
      • Sahambala
Grieco et al. (2010)
Norway
 
  • Troms og Finnmark
    • Porsanger
Nilsson et al. (1998)
Russia
 
  • Khabarovsk Krai
    • Ayano-Maysky district
      • Konder alkaline-ultrabasic massif
Kasatkin et al. (2025)
  • Krasnoyarsk Krai
    • Taymyrskiy Autonomous Okrug
      • Taimyr Peninsula
        • Norilsk-Talnakh Mining Region
          • Talnakh Cu-Ni Deposit
Spiridonov et al. (2011)
Kalugin et al. (2021)
  • Murmansk Oblast
    • Fedorovo-Pansky massif (Pana layered complex)
33rd International Geological Congress (2008)
Groshev +7 other references
Groshev +6 other references
Groshev +6 other references
Groshev +6 other references
Groshev +7 other references
33rd International Geological Congress (2008)
Groshev +6 other references
    • Monche tundra intrusion
Chashchin et al. (2018)
    • Monchegorsk
33 IGC excursion No 48
      • Yuzhnosopchinsky massif
Y.A. et al. (2019)
  • Republic of Karelia
    • Loukhsky District
      • Oulanka plutonic complex
        • Olanga River (Oulanka River)
Grishaenko et al. (2007)
  • Sverdlovsk Oblast
    • Prigorodny District
      • Volkovskii Cu-Fe-V-Au-Pd complex
Zaccarini et al. (2004) +1 other reference
Gurskaya (2002)
South Africa
 
  • Limpopo
    • Sekhukhune District Municipality
      • Fetakgomo Tubatse Local Municipality
Melcher et al. (2005)
    • Waterberg District Municipality
      • Modimolle-Mookgophong Local Municipality
        • Mookgophong
Oberthür et al. (2018)
      • Mogalakwena Local Municipality
        • Mokopane
          • Mogalakwena Mine
Holwell et al. (2006) +1 other reference
USA
 
  • Alaska
    • Kodiak Island Borough
      • Tugidak Island
Belkin et al. (2021)
  • Montana
Cabri et al. (1975) +1 other reference
    • Stillwater County
      • Blakely Creek
Volborth et al. (1986)
Gobla (2012)
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