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Mountkeithite

A valid IMA mineral species
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05278300017369912872507.jpg
Mountkeithite, etc.

Clear Creek Canyon, Goat Mountain, San Benito County, California, USA
08155930017554413305895.jpg
Mountkeithite

Mount Keith Open Pit, Mount Keith, Wiluna Shire, Western Australia, Australia
09356620017271925255605.jpg
Mountkeithite

Mount Keith Open Pit, Mount Keith, Wiluna Shire, Western Australia, Australia
09790620017367371057110.jpg
Mountkeithite, etc.

Clear Creek Canyon, Goat Mountain, San Benito County, California, USA
08019350017362250479034.jpg
Mountkeithite

Mount Keith Open Pit, Mount Keith, Wiluna Shire, Western Australia, Australia
09356620017271925255605.jpg
Mountkeithite

Mount Keith Open Pit, Mount Keith, Wiluna Shire, Western Australia, Australia
05278300017369912872507.jpg
Mountkeithite, etc.

Clear Creek Canyon, Goat Mountain, San Benito County, California, USA
08155930017554413305895.jpg
Mountkeithite

Mount Keith Open Pit, Mount Keith, Wiluna Shire, Western Australia, Australia
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About MountkeithiteHide

07484430017271925308904.jpg
Mount Keith mine pit September 1999

Mount Keith Open Pit, Mount Keith, Wiluna Shire, Western Australia, Australia
Formula:
[(Mg1-xFe3+x)(OH)2][SO4]x/2 · nH2O
(x < 0.5, n > 3x/2)
Colour:
Pale pink, white
Lustre:
Pearly
Hardness:
2
Specific Gravity:
2.12
Crystal System:
Hexagonal
Name:
Named by D.R. Hudson and M. Bussell after Mount Keith, Australia which includes the type locality. The mineral name was submitted to the IMA in 1977 and accepted in 1980 in a slightly modified form.
Usually found as a white to pink coating in vughs in weathered serpentine.


Unique IdentifiersHide

Mindat ID:
2796
Long-form identifier:
mindat:1:1:2796:6

IMA Classification of MountkeithiteHide

IMA status:
Approved
IMA Formula:
(Mg1-xFe3+x)(S6+O4)x/2(OH)2·nH2O (x < 0.5, n > 3x/2)
Approval year:
1980
First published:
1981
Type description reference:
Hudson, D.R., Bussell, M. (1981) Mountkeithite, a New Pyroaurite-Related Mineral with an Expanded Interlayer Containing Exchangeable MgSO4. Mineralogical Magazine: 44: 345-350.

Classification of MountkeithiteHide

Strunz-mindat (2026):
7.DD.35

7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
D : Sulfates (selenates, etc.) with additional anions, with H2O
D : With only medium-sized cations; sheets of edge-sharing octahedra
Dana 8th ed.:
32.4.3.1

32 : COMPOUND SULFATES
4 : Hydrated Compound Sulfates containing Hydroxyl or Halogen
Hey's CIM Ref.:
12.2.23

12 : Carbonates with other anions
2 : Carbonates with sulphate

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
MkeIMA–CNMNCWarr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43
MkeWarr (2020)Warr, L.N. (2020) Recommended abbreviations for the names of clay minerals and associated phases. Clay Minerals, 55, 261–264 doi:10.1180/clm.2020.30

Physical Properties of MountkeithiteHide

Lustre:
Pearly
Transparency:
Translucent
Colour:
Pale pink, white
Hardness:
2 on Mohs scale
Tenacity:
Fragile
Cleavage:
Perfect
{0001}
Density:
2.12 g/cm3 (Measured)    1.95 g/cm3 (Calculated)

Optical Data of MountkeithiteHide

Type:
Uniaxial (-)
RI values:
nω = 1.52 nε = 1.51
Max. Birefringence:
δ = 0.010
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.

Surface Relief:
Low (negative)
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 uniaxial interference figure - the conoscopic (convergent-light, Bertrand-lens-in) view, for a grain cut with the optic axis centred and vertical. The coloured rings are isochromatics, computed with the same physics as the Michel-Lévy bar above; the dark cross is the isogyre.

For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
Pleochroism:
Weak
Comments:
white to very pale pink.
Comments:
Uniaxial (–) or biaxial (–)
2V(meas.) = Small.

Chemistry of MountkeithiteHide

Mindat Formula:
[(Mg1-xFe3+x)(OH)2][SO4]x/2 · nH2O

(x < 0.5, n > 3x/2)
Elements listed:
Fe, H, Mg, O, S - search for minerals with similar chemistry

Crystallography of MountkeithiteHide

Crystal System:
Hexagonal
Cell Parameters:
a = 10.698 Å, c = 22.545 Å
Ratio:
a:c = 1 : 2.107
Unit Cell V:
2,234.53 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Scaly crystals, to 1 mm, in rosettes and whorllike aggregates
Comment:
Hexagonal (by analogy to pyroaurite). Point Group: n.d.; Space Group: n.d.

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
11.30 Å(100)
5.63 Å(80)
3.765 Å(60)
2.645 Å(40)
2.545 Å(40)
1.554 Å(50)
1.505 Å(30)

Geological EnvironmentHide

Paragenetic Mode(s):
Paragenetic ModeEarliest Age (Ga)
Stage 5: Initiation of plate tectonics<3.5-2.5
38 : Ophiolites
Stage 7: Great Oxidation Event<2.4
47a : [Near-surface hydration of prior minerals]
47b : [Sulfates and sulfites]

Type Occurrence of MountkeithiteHide

Type Locality:
ⓘ Mount Keith Open Pit, Mount Keith, Wiluna Shire, Western Australia, Australia
General Appearance of Type Material:
Friable aggregates and rosettes composed of soft flakes.
Place of Conservation of Type Material:
Western Australian Museum, Perth, Australia, M72.1991.
The Natural History Museum, London, England.
Geological Setting of Type Material:
Low-temperature hydrothermal vein in a nickel deposit.
Associated Minerals at Type Locality:
HexahydriteMagnesiteMagnetiteMorenositePyrite
PyroauriteStichtite
Reference:
Hudson, D.R., Bussell, M. (1981) Mountkeithite, a New Pyroaurite-Related Mineral with an Expanded Interlayer Containing Exchangeable MgSO4. Mineralogical Magazine: 44: 345-350.

Synonyms of MountkeithiteHide

Other Language Names for MountkeithiteHide

Relationship of Mountkeithite to other SpeciesHide

Member of:
Glaucocerinite Group > Hydrotalcite Supergroup
Other Members of Glaucocerinite Group:
Carrboydite(Ni1-xAlx)(SO4)x/2(OH)2 · nH2OHex.
Glaucocerinite(Zn1-xAlx)(OH)2(SO4)x/2 · nH2OHex.
Hydrohonessite(Ni1-xFe3+x)(OH)2(SO4)x/2 · nH2OHex.
Hydrowoodwardite(Cu1-xAlx)(OH)2[SO4]x/2 · nH2OTrig. 3m(32/m) : R3m
Zincaluminite(Zn1-xAlx)(SO4)x/2(OH)2 · nH2O

Common AssociatesHide

Associations Based on Photo Data:
4 photos of Mountkeithite associated with ArtiniteMg2(CO3)(OH)2 · 3H2O
4 photos of Mountkeithite associated with Serpentine SubgroupD3[Si2O5](OH)4
1 photo of Mountkeithite associated with StichtiteMg6Cr3+2(OH)16[CO3] · 4H2O
1 photo of Mountkeithite associated with Spinel SubgroupA2+D3+2O4

Related Minerals - Strunz-mindat GroupingHide

7.DD.AsagiiteNiCu4(SO4)2(OH)6 · 6H2OMon. 2/m : P21/b
7.DD.05FelsőbányaiteAl4(SO4)(OH)10 · 4H2OMon. 2 : P21
7.DD.07LlantenesiteCu6Al[SeO4](OH)12Cl · 3H2OTrig. 3m : P31c
7.DD.10LangiteCu4(SO4)(OH)6 · 2H2OMon. m
7.DD.10FehriteMgCu4(SO4)2(OH)6 · 6H2OMon. 2/m : P21/b
7.DD.10PosnjakiteCu4(SO4)(OH)6 · H2OMon. m : Pm
7.DD.10WroewolfeiteCu4(SO4)(OH)6 · 2H2OMon. m : Pm
7.DD.10GobeliniteCoCu4(SO4)2(OH)6 · 6H2OMon. 2/m : P21/m
7.DD.15KobyasheviteCu5(SO4)2(OH)6 · 4H2OTric. 1 : P1
7.DD.15SpangoliteCu6Al(SO4)(OH)12Cl · 3H2OTrig. 3m : P31c
7.DD.15'Unnamed (Dimorph of Devilline)'CaCu4(SO4)2(OH)6 · 3H2OMon. 2/m : P21/b
7.DD.20KtenasiteZnCu4(SO4)2(OH)6 · 6H2OMon. 2/m : P21/b
7.DD.25ChristeliteCu2Zn3(SO4)2(OH)6 · 4H2OTric. 1 : P1
7.DD.30EdwardsiteCu3Cd2(SO4)2(OH)6 · 4H2O Mon. 2/m : P21/b
7.DD.30NiedermayriteCdCu4(SO4)2(OH)6 · 4H2OMon. 2/m : P21/m
7.DD.30SerpieriteCa(Cu2+,Zn2+)4(S6+O4)2(OH)6 · 3H2OMon. 2/m : B2/b
7.DD.30CampigliaiteMn2+Cu4(SO4)2(OH)6 · 4H2OMon. 2 : B2
7.DD.30OrthoserpieriteCa(Cu,Zn)4(SO4)2(OH)6 · 3H2OOrth. mm2 : Pca21
7.DD.30DevillineCaCu4(SO4)2(OH)6 · 3H2OMon. 2/m : P21/b
7.DD.35ShigaiteMn6Al3(OH)18[Na(H2O)6](SO4)2 · 6H2OTrig. 3 : R3
7.DD.35Zincaluminite(Zn1-xAlx)(SO4)x/2(OH)2 · nH2O
7.DD.35ZincowoodwarditeZn1-xAlx(OH)2[SO4]x/2 · nH2OTrig.
7.DD.35NatroglaucoceriniteZn6Al3(OH)18[Na(H2O)6](SO4)2 · 6H2OHex.
7.DD.35Hydrowoodwardite(Cu1-xAlx)(OH)2[SO4]x/2 · nH2OTrig. 3m(32/m) : R3m
7.DD.35Honessite(Ni1-xFe3+x)(OH)2[SO4]x/2 · nH2OTrig.
7.DD.35Carrboydite(Ni1-xAlx)(SO4)x/2(OH)2 · nH2OHex.
7.DD.35Glaucocerinite(Zn1-xAlx)(OH)2(SO4)x/2 · nH2OHex.
7.DD.35WermlanditeMg7Al2(OH)18[Ca(H2O)6][SO4]2 · 6H2OTrig. 3m(32/m) : P3c1
7.DD.35NikischeriteFe2+6Al3(OH)18[Na(H2O)6](SO4)2 · 6H2OTrig. 3 : R3
7.DD.35Hydrohonessite(Ni1-xFe3+x)(OH)2(SO4)x/2 · nH2OHex.
7.DD.35WoodwarditeCu1-xAlx(OH)2(SO4)x/2 · nH2OTrig. 3m(32/m) : R3m
7.DD.35MotukoreaiteMg6Al3(OH)18[Na(H2O)6][SO4]2 · 6H2OTrig. 3m(32/m) : R3m
7.DD.40Lawsonbauerite(Mn2+,Mg)9Zn4(SO4)2(OH)22 · 8H2OMon. 2/m : P21/b
7.DD.40Torreyite(Mg,Mn2+)7◻2Mn2+2Zn4(SO4)2(OH)22 · 8H2OMon. 2/m : P21/b
7.DD.40IsseliteCu6(SO4)(OH)10(H2O)4 · H2OOrth. mm2 : Pmn21
7.DD.45MooreiteMg9◻2Mn2Zn4(SO4)2(OH)26 · 8H2OMon. 2/m : P2/b
7.DD.45Hodgesmithite(Cu,Zn)6Zn(SO4)2(OH)10 · 3H2OTrig. 3 : P3
7.DD.47LahnsteiniteZn4(SO4)(OH)6 · 3H2OTric. 1 : P1
7.DD.50NamuwiteZn4(SO4)(OH)6 · 4H2OTrig. 3 : P3
7.DD.50Minohlite(Cu,Zn)7(SO4)2(OH)10 · 8H2OHex.
7.DD.52LauraniiteCu6Cd2(SO4)2(OH)12 · 5H2OMon. 2/m : P21/b
7.DD.55BechereriteZn7Cu(OH)13[(SiO(OH)3(SO4)]Trig. 3 : P3
7.DD.60Ramsbeckite(Cu,Zn)15(SO4)4(OH)22 · 6H2OMon. 2/m
7.DD.65VonbezingiteCa6Cu3(SO4)3(OH)12 · 2H2OMon. 2/m : P21/b
7.DD.70RedgilliteCu6(SO4)(OH)10 · H2OMon. 2/m : P21/b
7.DD.75NickelalumiteNiAl4(SO4)(OH)12(H2O)3Mon. 2/m
7.DD.75KyrgyzstaniteZnAl4(SO4)(OH)12 · 3H2OMon. 2/m : P21/b
7.DD.75ChalcoalumiteCuAl4(SO4)(OH)12 · 3H2OMon. 2 : P21
7.DD.80Schulenbergite(Cu,Zn)7(SO4)2(OH)10 · 3H2OTrig. 3
7.DD.80'UM1992-30-SO:CCuHZn'(Zn,Cu)7(SO4,CO3)2(OH)10 · 3H2OTrig. 3 : P3
7.DD.80ThérèsemagnaniteNaCo4(SO4)(OH)6Cl · 6H2OTrig. 3 : P3
7.DD.80GuarinoiteZn6(SO4)(OH)10 · 5H2OHex.
7.DD.85MontetrisaiteCu6(SO4)(OH)10 · 2H2OOrth. mm2 : Cmc21

Other InformationHide

Notes:
soluble, with effervescence, in dilute HCl.
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 MountkeithiteHide

References for MountkeithiteHide

Localities for MountkeithiteHide

Showing 6 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.
Hide all sections | Show all sections

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.
Australia
 
  • Tasmania
    • West Coast municipality
      • Zeehan mining district
        • Dundas mineral field
Bottrill et al. (2008)
  • Western Australia
    • Leonora Shire
      • Leinster
Ben Grguric
    • Wiluna Shire
      • Lake Way Station
Grguric et al. (2013)
Wilson et al. (2014)
MM 1981
USA
 
  • California
    • San Benito County
      • Goat Mountain
Sorrell (n.d.) +1 other reference
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