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Adventure mine, Greenland, Greenland Township, Ontonagon Co., Michigan, USA

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Latitude & Longitude (WGS84): 46° 46' 27'' North , 89° 4' 54'' West
Latitude & Longitude (decimal): 46.77433,-89.08191
Other regions containing this locality:Keweenaw Peninsula, Michigan, USA
Köppen climate type:Dfb : Warm-summer humid continental climate
Other/historical region names associated with this locality:Adventure Consolidated Mine

An underground copper mine consisting of three shafts and at least one adit. It is located just south of the town of Greenland, about 15 miles SE of Ontonagon. The Adventure Mining Co. organized in 1850. In 1858 it purchased the Merchants Co. property. In 1870 the company was sold and reorganized under the same name. In 1898, the company was sold again and reorganized under the Adventure Consolidated Copper Co. This consolidation included the Adventure, Hilton, and Knowlton mines. The company suspended all operation in October of 1917. The mine produced approx. 11 million lbs. of refined copper. The mine is currently open as a tourist attraction, and tours are given underground during the summer months. Minerals that can be found here include copper, silver, and quartz.

Mineral List

13 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

1000 - 1200 Ma

ID: 2928167
Portage Lake Volcanics

Age: Stenian (1000 - 1200 Ma)

Stratigraphic Name: Portage Lake Volcanics

Description: Lava flows, mostly basalt, andesite and felsite flows and subordinate interflow sedimentary rocks.

Comments: This unit is the same as unit Yp on paper map of Sims (1992). Description is taken from that unit description.

Lithology: Major:{basalt}, Minor:{basaltic andesite}, Incidental:{rhyolite, sandstone mudstone}

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]

1000 - 1600 Ma

ID: 3190266
Mesoproterozoic volcanic rocks

Age: Mesoproterozoic (1000 - 1600 Ma)

Comments: Mid-Continent Rift

Lithology: Bimodal volcanic rocks

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]

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.


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Henwood, W.J. (1871): Observations on Metalliferous Deposits: On the Native Copper of Lake Superior. Transactions of the Royal Geological Society of Cornwall 8(1), 385-489.
Rocks & Minerals 58: 112
Rocks & Minerals 65: 240
U.S.G.S. Prof. Paper 144.

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