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Rocky Boy Stock Occurrence, Hill County, Montana, USAi
| Regional Level Types | |
|---|---|
| Rocky Boy Stock Occurrence | Occurrence |
| Hill County | County |
| Montana | State |
| USA | Country |
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Latitude & Longitude (WGS84):
48° 10' North , 109° 42' West
Latitude & Longitude (decimal):
Type:
Köppen climate type:
Nearest Settlements:
| Place | Population | Distance |
|---|---|---|
| Parker School | 340 (2011) | 9.7km |
| Rocky Boy's Agency | 355 (2011) | 11.3km |
| Saint Pierre | 350 (2011) | 11.8km |
| Sangrey | 306 (2011) | 15.8km |
| Azure | 286 (2011) | 16.6km |
Commodities (Major) - Niobium
Development Status: Occurrence
Host Rock: Syenite
The largest intrusive feature in the Bearpaw Mountains is the Rocky Boy stock, which covers an area of approximately 30 km2. This composite intrusion comprises two principal series: a strongly undersaturated, high-potassium shonkinite series and a slightly undersaturated, potassic monzonite series. Despite its designation, the monzonite series is somewhat misclassified, as its rocks are predominantly mafic monzosyenites and melasyenites, with K-feldspar to plagioclase ratios ranging from 2:1 to 3:1. Rare dikes of carbonatite, biotite gabbro, and latite also occur within the stock.
Crosscutting relationships among the units of the Rocky Boy stock reveal a chronological sequence of emplacement, from oldest to youngest: pyroxenite, shonkinite, monzosyenite, syenite, and carbonatite. Shonkinite constitutes the dominant rock type of the stock. 40K/40Ar dates from the Rocky Boy stock align closely with those of the volcanic rocks, ranging from 54 Ma to 50 Ma.
Select Mineral List Type
Standard Detailed Gallery Strunz Chemical ElementsCommodity List
This is a list of exploitable or exploited mineral commodities recorded at this locality.Mineral List
5 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 DiagramDetailed Mineral List:
Gallery:
List of minerals arranged by Strunz 10th Edition classification
| Group 5 - Nitrates and Carbonates | |||
|---|---|---|---|
| ⓘ | Calcite | 5.AB.05 | CaCO3 |
| ⓘ | Burbankite | 5.AC.30 | (Na,Ca)3(Sr,Ba,Ce)3(CO3)5 |
| ⓘ | Calkinsite-(Ce) | 5.CC.25 | (Ce,La)2(CO3)3 · 4H2O |
| Group 7 - Sulphates, Chromates, Molybdates and Tungstates | |||
| ⓘ | Baryte | 7.AD.35 | BaSO4 |
| Group 9 - Silicates | |||
| ⓘ | Aegirine | 9.DA.25 | NaFe3+Si2O6 |
| Unclassified | |||
| ⓘ | 'Biotite' | - | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
| ⓘ | 'Ancylite' | - | |
| ⓘ | 'Plagioclase' | - | (Na,Ca)[(Si,Al)AlSi2]O8 |
| ⓘ | 'K Feldspar' | - | |
| ⓘ | 'Lanthanite' | - | |
List of minerals for each chemical element
| H | Hydrogen | |
|---|---|---|
| H | ⓘ Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
| H | ⓘ Calkinsite-(Ce) | (Ce,La)2(CO3)3 · 4H2O |
| C | Carbon | |
| C | ⓘ Burbankite | (Na,Ca)3(Sr,Ba,Ce)3(CO3)5 |
| C | ⓘ Calcite | CaCO3 |
| C | ⓘ Calkinsite-(Ce) | (Ce,La)2(CO3)3 · 4H2O |
| O | Oxygen | |
| O | ⓘ Aegirine | NaFe3+Si2O6 |
| O | ⓘ Baryte | BaSO4 |
| O | ⓘ Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
| O | ⓘ Burbankite | (Na,Ca)3(Sr,Ba,Ce)3(CO3)5 |
| O | ⓘ Calcite | CaCO3 |
| O | ⓘ Calkinsite-(Ce) | (Ce,La)2(CO3)3 · 4H2O |
| O | ⓘ Plagioclase | (Na,Ca)[(Si,Al)AlSi2]O8 |
| F | Fluorine | |
| F | ⓘ Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
| Na | Sodium | |
| Na | ⓘ Aegirine | NaFe3+Si2O6 |
| Na | ⓘ Burbankite | (Na,Ca)3(Sr,Ba,Ce)3(CO3)5 |
| Na | ⓘ Plagioclase | (Na,Ca)[(Si,Al)AlSi2]O8 |
| Mg | Magnesium | |
| Mg | ⓘ Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
| Al | Aluminium | |
| Al | ⓘ Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
| Al | ⓘ Plagioclase | (Na,Ca)[(Si,Al)AlSi2]O8 |
| Si | Silicon | |
| Si | ⓘ Aegirine | NaFe3+Si2O6 |
| Si | ⓘ Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
| Si | ⓘ Plagioclase | (Na,Ca)[(Si,Al)AlSi2]O8 |
| S | Sulfur | |
| S | ⓘ Baryte | BaSO4 |
| K | Potassium | |
| K | ⓘ Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
| Ca | Calcium | |
| Ca | ⓘ Burbankite | (Na,Ca)3(Sr,Ba,Ce)3(CO3)5 |
| Ca | ⓘ Calcite | CaCO3 |
| Ca | ⓘ Plagioclase | (Na,Ca)[(Si,Al)AlSi2]O8 |
| Ti | Titanium | |
| Ti | ⓘ Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
| Fe | Iron | |
| Fe | ⓘ Aegirine | NaFe3+Si2O6 |
| Fe | ⓘ Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
| Sr | Strontium | |
| Sr | ⓘ Burbankite | (Na,Ca)3(Sr,Ba,Ce)3(CO3)5 |
| Ba | Barium | |
| Ba | ⓘ Baryte | BaSO4 |
| Ba | ⓘ Burbankite | (Na,Ca)3(Sr,Ba,Ce)3(CO3)5 |
| La | Lanthanum | |
| La | ⓘ Calkinsite-(Ce) | (Ce,La)2(CO3)3 · 4H2O |
| Ce | Cerium | |
| Ce | ⓘ Burbankite | (Na,Ca)3(Sr,Ba,Ce)3(CO3)5 |
| Ce | ⓘ Calkinsite-(Ce) | (Ce,La)2(CO3)3 · 4H2O |
Other Databases
| Link to USGS MRDS: | 10009158 |
|---|
Other Regions, Features and Areas containing this locality
North AmericaContinent
North America PlateTectonic Plate
- Little Belt ArcVolcanic Arc
- Medicine Hat DomainDomain
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References
[1]Oyelayo, James A.; Zhou, Xiaobing; Roy, Sukanta (2026) Two-stage rare earth element mineralization in the Bowery Peak carbonatite dyke, Bearpaw Mountains, Montana, USA: An integrated mineralogical, geochemical, and geophysical study. Geoscience Frontiers, 17 (3). 102267 doi:10.1016/j.gsf.2026.102267
