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Shonkin Sag laccolith, Highwood Mountains, Chouteau County, Montana, USAi
Regional Level Types
Shonkin Sag laccolith- not defined -
Highwood MountainsMountain Range
Chouteau CountyCounty
MontanaState
USACountry

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Latitude & Longitude (WGS84):
47° 33' 0'' North , 110° 17' 34'' West
Latitude & Longitude (decimal):
47.55013,-110.29293
GeoHash:
G#: c83wd0pps
GRN:
N32W55
Köppen climate type:
BSk : Cold semi-arid (steppe) climate
Nearest Settlements:
PlacePopulationDistance
Geraldine263 (2017)6.3km
Denton248 (2017)36.5km
Highwood176 (2011)37.5km
Fort Benton1,460 (2017)40.9km
Stanford381 (2017)44.4km
Mindat Locality ID:
240605
Long-form identifier:
mindat:1:2:240605:6
GUID (UUID V4):
0


The type locality for the rock type "shonkinite" which, together with syenite comprise this 1.5 km wide and 60 m thick laccolith.

Select Mineral List Type

Standard Detailed Gallery Strunz Chemical Elements

Mineral List


21 valid minerals.

Rock Types Recorded

Note: data is currently VERY limited. Please bear with us while we work towards adding this information!

Select Rock List Type

Alphabetical List Tree Diagram

Detailed Mineral List:

ⓘ Aegirine
Formula: NaFe3+Si2O6
ⓘ Andradite
Formula: Ca3Fe3+2(SiO4)3
ⓘ Andradite var. Melanite
Formula: Ca3Fe3+2(SiO4)3
ⓘ Annite
Formula: KFe2+3(AlSi3O10)(OH)2
ⓘ 'Apatite'
Formula: Ca5(PO4)3(Cl/F/OH)
ⓘ Arfvedsonite
Formula: [Na][Na2][Fe2+4Fe3+]Si8O22(OH)2
ⓘ Augite
Formula: (CaxMgyFez)(Mgy1Fez1)Si2O6
ⓘ 'Biotite'
Formula: K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
ⓘ 'Britholite Group'
Formula: (REE,Ca)5[(Si,P)O4]3X
ⓘ Calcite
Formula: CaCO3
ⓘ 'Chabazite'
ⓘ Diopside
Formula: CaMgSi2O6
ⓘ Diopside var. Salite
Formula: CaMgSi2O6
ⓘ 'Fayalite-Forsterite Series'
ⓘ Fluorapatite
Formula: Ca5(PO4)3F
ⓘ Fluorite
Formula: CaF2
ⓘ Forsterite
Formula: Mg2SiO4
ⓘ 'Garnet Group'
Formula: X3Z2(SiO4)3
ⓘ Hematite
Formula: Fe2O3
ⓘ Leucite
Formula: K(AlSi2O6)
ⓘ Magnetite
Formula: Fe2+Fe3+2O4
ⓘ Magnetite var. Titanium-bearing Magnetite
Formula: Fe2+(Fe3+,Ti)2O4
ⓘ Natrolite
Formula: Na2Al2Si3O10 · 2H2O
ⓘ Nepheline
Formula: Na3K(Al4Si4O16)
Description: altered to natrolite and stilbite
ⓘ Phlogopite
Formula: KMg3(AlSi3O10)(OH)2
ⓘ 'Pseudoleucite'
ⓘ Pyrite
Formula: FeS2
ⓘ Pyrrhotite
Formula: Fe1-xS
ⓘ Sanidine
Formula: K(AlSi3O8)
ⓘ Sodalite
Formula: Na4(Si3Al3)O12Cl
ⓘ 'Stilbite Subgroup'
Formula: M6-7[Al8-9Si27-28O72] · nH2O
ⓘ Titanite
Formula: CaTi(SiO4)O

Gallery:

List of minerals arranged by Strunz 10th Edition classification

Group 2 - Sulphides and Sulfosalts
ⓘPyrrhotite2.CC.10Fe1-xS
ⓘPyrite2.EB.05aFeS2
Group 3 - Halides
ⓘFluorite3.AB.25CaF2
Group 4 - Oxides and Hydroxides
ⓘMagnetite4.BB.05Fe2+Fe3+2O4
ⓘvar. Titanium-bearing Magnetite4.BB.05Fe2+(Fe3+,Ti)2O4
ⓘHematite4.CB.05Fe2O3
Group 5 - Nitrates and Carbonates
ⓘCalcite5.AB.05CaCO3
Group 8 - Phosphates, Arsenates and Vanadates
ⓘFluorapatite8.BN.05Ca5(PO4)3F
Group 9 - Silicates
ⓘForsterite9.AC.05Mg2SiO4
ⓘAndradite9.AD.25Ca3Fe3+2(SiO4)3
ⓘvar. Melanite9.AD.25Ca3Fe3+2(SiO4)3
ⓘTitanite9.AG.15CaTi(SiO4)O
ⓘAugite9.DA.15(CaxMgyFez)(Mgy1Fez1)Si2O6
ⓘDiopside9.DA.15CaMgSi2O6
ⓘvar. Salite9.DA.15CaMgSi2O6
ⓘAegirine9.DA.25NaFe3+Si2O6
ⓘArfvedsonite9.DE.25[Na][Na2][Fe2+4Fe3+]Si8O22(OH)2
ⓘAnnite9.EC.20KFe2+3(AlSi3O10)(OH)2
ⓘPhlogopite9.EC.20KMg3(AlSi3O10)(OH)2
ⓘNepheline9.FA.05Na3K(Al4Si4O16)
ⓘSanidine9.FA.30K(AlSi3O8)
ⓘSodalite9.FB.10Na4(Si3Al3)O12Cl
ⓘNatrolite9.GA.05Na2Al2Si3O10 · 2H2O
ⓘLeucite9.GB.05K(AlSi2O6)
Unclassified
ⓘ'Biotite'-K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
ⓘ'Chabazite'-
ⓘ'Stilbite Subgroup'-M6-7[Al8-9Si27-28O72] · nH2O
ⓘ'Fayalite-Forsterite Series'-
ⓘ'Garnet Group'-X3Z2(SiO4)3
ⓘ'Apatite'-Ca5(PO4)3(Cl/F/OH)
ⓘ'Britholite Group'-(REE,Ca)5[(Si,P)O4]3X
ⓘ'Pseudoleucite'-

List of minerals for each chemical element

HHydrogen
Hⓘ AnniteKFe32+(AlSi3O10)(OH)2
Hⓘ Arfvedsonite[Na][Na2][Fe42+Fe3+]Si8O22(OH)2
Hⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Hⓘ NatroliteNa2Al2Si3O10 · 2H2O
Hⓘ PhlogopiteKMg3(AlSi3O10)(OH)2
Hⓘ Stilbite SubgroupM6-7[Al8-9Si27-28O72] · nH2O
Hⓘ ApatiteCa5(PO4)3(Cl/F/OH)
CCarbon
Cⓘ CalciteCaCO3
OOxygen
Oⓘ AegirineNaFe3+Si2O6
Oⓘ AndraditeCa3Fe23+(SiO4)3
Oⓘ AnniteKFe32+(AlSi3O10)(OH)2
Oⓘ Arfvedsonite[Na][Na2][Fe42+Fe3+]Si8O22(OH)2
Oⓘ Augite(CaxMgyFez)(Mgy1Fez1)Si2O6
Oⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Oⓘ CalciteCaCO3
Oⓘ DiopsideCaMgSi2O6
Oⓘ FluorapatiteCa5(PO4)3F
Oⓘ ForsteriteMg2SiO4
Oⓘ HematiteFe2O3
Oⓘ LeuciteK(AlSi2O6)
Oⓘ MagnetiteFe2+Fe23+O4
Oⓘ NephelineNa3K(Al4Si4O16)
Oⓘ NatroliteNa2Al2Si3O10 · 2H2O
Oⓘ PhlogopiteKMg3(AlSi3O10)(OH)2
Oⓘ SanidineK(AlSi3O8)
Oⓘ SodaliteNa4(Si3Al3)O12Cl
Oⓘ Stilbite SubgroupM6-7[Al8-9Si27-28O72] · nH2O
Oⓘ TitaniteCaTi(SiO4)O
Oⓘ Magnetite var. Titanium-bearing MagnetiteFe2+(Fe3+,Ti)2O4
Oⓘ Andradite var. MelaniteCa3Fe23+(SiO4)3
Oⓘ Fayalite-Forsterite Series
Oⓘ Garnet GroupX3Z2(SiO4)3
Oⓘ Diopside var. SaliteCaMgSi2O6
Oⓘ ApatiteCa5(PO4)3(Cl/F/OH)
Oⓘ Britholite Group(REE,Ca)5[(Si,P)O4]3X
FFluorine
Fⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Fⓘ FluorapatiteCa5(PO4)3F
Fⓘ FluoriteCaF2
Fⓘ ApatiteCa5(PO4)3(Cl/F/OH)
NaSodium
Naⓘ AegirineNaFe3+Si2O6
Naⓘ Arfvedsonite[Na][Na2][Fe42+Fe3+]Si8O22(OH)2
Naⓘ NephelineNa3K(Al4Si4O16)
Naⓘ NatroliteNa2Al2Si3O10 · 2H2O
Naⓘ SodaliteNa4(Si3Al3)O12Cl
MgMagnesium
Mgⓘ Augite(CaxMgyFez)(Mgy1Fez1)Si2O6
Mgⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Mgⓘ DiopsideCaMgSi2O6
Mgⓘ ForsteriteMg2SiO4
Mgⓘ PhlogopiteKMg3(AlSi3O10)(OH)2
Mgⓘ Fayalite-Forsterite Series
Mgⓘ Diopside var. SaliteCaMgSi2O6
AlAluminium
Alⓘ AnniteKFe32+(AlSi3O10)(OH)2
Alⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Alⓘ LeuciteK(AlSi2O6)
Alⓘ NephelineNa3K(Al4Si4O16)
Alⓘ NatroliteNa2Al2Si3O10 · 2H2O
Alⓘ PhlogopiteKMg3(AlSi3O10)(OH)2
Alⓘ SanidineK(AlSi3O8)
Alⓘ SodaliteNa4(Si3Al3)O12Cl
Alⓘ Stilbite SubgroupM6-7[Al8-9Si27-28O72] · nH2O
SiSilicon
Siⓘ AegirineNaFe3+Si2O6
Siⓘ AndraditeCa3Fe23+(SiO4)3
Siⓘ AnniteKFe32+(AlSi3O10)(OH)2
Siⓘ Arfvedsonite[Na][Na2][Fe42+Fe3+]Si8O22(OH)2
Siⓘ Augite(CaxMgyFez)(Mgy1Fez1)Si2O6
Siⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Siⓘ DiopsideCaMgSi2O6
Siⓘ ForsteriteMg2SiO4
Siⓘ LeuciteK(AlSi2O6)
Siⓘ NephelineNa3K(Al4Si4O16)
Siⓘ NatroliteNa2Al2Si3O10 · 2H2O
Siⓘ PhlogopiteKMg3(AlSi3O10)(OH)2
Siⓘ SanidineK(AlSi3O8)
Siⓘ SodaliteNa4(Si3Al3)O12Cl
Siⓘ Stilbite SubgroupM6-7[Al8-9Si27-28O72] · nH2O
Siⓘ TitaniteCaTi(SiO4)O
Siⓘ Andradite var. MelaniteCa3Fe23+(SiO4)3
Siⓘ Fayalite-Forsterite Series
Siⓘ Garnet GroupX3Z2(SiO4)3
Siⓘ Diopside var. SaliteCaMgSi2O6
Siⓘ Britholite Group(REE,Ca)5[(Si,P)O4]3X
PPhosphorus
Pⓘ FluorapatiteCa5(PO4)3F
Pⓘ ApatiteCa5(PO4)3(Cl/F/OH)
Pⓘ Britholite Group(REE,Ca)5[(Si,P)O4]3X
SSulfur
Sⓘ PyriteFeS2
Sⓘ PyrrhotiteFe1-xS
ClChlorine
Clⓘ SodaliteNa4(Si3Al3)O12Cl
Clⓘ ApatiteCa5(PO4)3(Cl/F/OH)
KPotassium
Kⓘ AnniteKFe32+(AlSi3O10)(OH)2
Kⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Kⓘ LeuciteK(AlSi2O6)
Kⓘ NephelineNa3K(Al4Si4O16)
Kⓘ PhlogopiteKMg3(AlSi3O10)(OH)2
Kⓘ SanidineK(AlSi3O8)
CaCalcium
Caⓘ AndraditeCa3Fe23+(SiO4)3
Caⓘ Augite(CaxMgyFez)(Mgy1Fez1)Si2O6
Caⓘ CalciteCaCO3
Caⓘ DiopsideCaMgSi2O6
Caⓘ FluorapatiteCa5(PO4)3F
Caⓘ FluoriteCaF2
Caⓘ TitaniteCaTi(SiO4)O
Caⓘ Andradite var. MelaniteCa3Fe23+(SiO4)3
Caⓘ Diopside var. SaliteCaMgSi2O6
Caⓘ ApatiteCa5(PO4)3(Cl/F/OH)
Caⓘ Britholite Group(REE,Ca)5[(Si,P)O4]3X
TiTitanium
Tiⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Tiⓘ TitaniteCaTi(SiO4)O
Tiⓘ Magnetite var. Titanium-bearing MagnetiteFe2+(Fe3+,Ti)2O4
FeIron
Feⓘ AegirineNaFe3+Si2O6
Feⓘ AndraditeCa3Fe23+(SiO4)3
Feⓘ AnniteKFe32+(AlSi3O10)(OH)2
Feⓘ Arfvedsonite[Na][Na2][Fe42+Fe3+]Si8O22(OH)2
Feⓘ Augite(CaxMgyFez)(Mgy1Fez1)Si2O6
Feⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Feⓘ HematiteFe2O3
Feⓘ MagnetiteFe2+Fe23+O4
Feⓘ PyriteFeS2
Feⓘ PyrrhotiteFe1-xS
Feⓘ Magnetite var. Titanium-bearing MagnetiteFe2+(Fe3+,Ti)2O4
Feⓘ Andradite var. MelaniteCa3Fe23+(SiO4)3
Feⓘ Fayalite-Forsterite Series

Other Regions, Features and Areas containing this locality

North AmericaContinent
North America PlateTectonic Plate

This page contains all mineral locality references listed on mindat.org. This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in mindat.org without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.

References

Barksdale, J.D. (1937) The Shonkin Sag Laccolith. American Journal of Science, 23, 321–359.
W. P. Nash, Lawrence M. Monson, (1987) "Shonkin Sag laccolith; A differentiated alkaline intrusion, Highwood Mountains, Montana", Rocky Mountain Section of the Geological Society of America, Stanley S. Beus
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