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Geis Mine (Red Metal Claim group; Gies Mine; Elk Peak project; Bertha claim group), Cone Butte Sub-District, Warm Springs District (Gilt Edge District; Gold Hill District; Maiden District), Fergus Co., Montana, USA

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Latitude & Longitude (WGS84): 47° 13' 17'' North , 109° 9' 44'' West
Latitude & Longitude (decimal): 47.22132,-109.16219
Köppen climate type:Dfb : Warm-summer humid continental climate

A group of 11 patented claims between Armells Creek and Ford Creek about 3 miles NW of old Fort Maginnis.

Mineralization is a Ag-Pb-Zn deposit along the contact between limestone and syenite porphyry.

Property is developed by adits and shafts.

Average grade of 13.7g/t, but high grade to 13,714 g/t.
Unknown of composition - (Ag,Cu)9(As,Sb)(Te,S)6

Mineral List

38 valid minerals.

Regional Geology

This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.

Click on geological units on the map for more information. Click here to view full-screen map on

Late Cretaceous
66 - 100.5 Ma

ID: 3188050
Mesozoic sedimentary rocks

Age: Late Cretaceous (66 - 100.5 Ma)

Lithology: Siltstone,shale,sandstone

Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529. [154]

100.5 - 113 Ma

ID: 2983530
Thermopolis and Fall River Formations

Age: Early Cretaceous (100.5 - 113 Ma)

Stratigraphic Name: Thermopolis Shale; Fall River Formation

Description: Thermopolis Formation (Kt): Dark gray to black shale with subordinate siltstone beds. Middle part of formation contains one or more thin sandstone beds with chert pebble horizons where Muddy Sandstone is not present. Offshore marine. Thickness as much as 305 m (1,000 ft). Fall River Formation (Kfr): Gray and brown, fine- to medium-grained, quartzose sandstone with thin interbeds of dark gray shale. Nearshore marine. Thickness as much as 70 m (1,214 ft).

Lithology: Major:{shale,sandstone}, Minor:{siltstone}, Incidental:{chert}

Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052. [133]

Data and map coding provided by, used under Creative Commons Attribution 4.0 License

This page contains all mineral locality references listed on 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 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.


Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
- Zhang, X., and Spry, P.G. (1991): Mineralogical and fluid inclusion characteristics of the epithermal Gies gold-silver telluride deposit, Judith Mountains, Fergus County, Montana: A preliminary study, in Baker, D.W., and Berg, R.B., eds., Guidebook of the central Montana alkalic belt, Montana Bureau of Mines and Geology Special Publication 100, p. 63-76.
- Zhang, X., and Spry, P.G. (1994): Petrological, mineralogical, fluid inclusion and stable isotope studies of the Gies gold-silver telluride deposit, Judith Mountains, Montana. Economic Geology, 89, 602-628.
- Bindi, L., Spry, P.G., Pratesi, G. (2006): Lenaite from the Gies gold–silver telluride deposit, Judith Mountains, Montana, U.S.A.: occurrence, composition, and crystal structure. Canadian Mineralogist 44, 207-212.

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