Seneca No. 1 Shaft: Copper & Datolite Rockhounding in Keweenaw County, Michigan
- Minerals reported
- 3
- Elevation
- 1,030 ft
- Best months
- April to October
Seneca No. 1 Shaft is a mapped rockhounding spot in Keweenaw County, Michigan. Reported finds include copper, datolite, prehnite. Below: coordinates, access notes, nearby spots, and trip-planning links.
Plan your visit
Permission required before collecting
- County
- Keweenaw County
- State
- Michigan
- Nearest road
- Seneca Road
- Postcode
- 49950
- Coordinates
- 47.31132, -88.36219
Coordinates are approximate. Confirm the exact ground in the RockHoundR app, where land overlays show which agency manages the area.
Land & collecting status
Permission required before collecting
Requires landowner or agency permission before any collecting. Do not enter without explicit authorization.
Public-land rules vary by agency, season, and field office. The RockHoundR app pulls live BLM, USFS, NPS, and tribal overlays so you can see exactly which agency manages the ground at this spot.
Best time to visit Seneca No. 1 Shaft
Comfortable months (45 to 90°F highs)
Best months: April to October. Typical highs run 76°F in midsummer and 22°F in midwinter, with winter lows near 10°F.
Climate normals: NOAA 1991-2020 monthlies, HANCOCK HOUGHTON CO AP station (11 mi away).
Geology at Seneca No. 1 Shaft
This spot sits on Portage Lake Volcanics, mapped as basalt that formed roughly 1200 to 1000 million years ago. Copper minerals such as malachite and chrysocolla typically show up where mineralized rock like this has weathered and oxidized near old workings.
- Mapped unit
- Portage Lake Volcanics
- Age
- 1200–1000 Ma (Mesoproterozoic)
- Rock types
- basalt
- Elevation
- 1,030 ft
Geologic mapping via Macrostrat and the underlying state geological survey maps (CC BY 4.0). Bedrock at the surface can vary within a mapped unit.
Today's weather
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Get the appSources & verification
Spot details combine the public RockHoundR location dataset, normalized mineral labels, agency land-status checks in the app, and community submissions. Coordinates are approximate until verified in the field.
State guidance last verified:
- Michigan DNR, Rockhounding rules
- Michigan Geological Survey
- Isle Royale National Park, Rules
- Community submissions reviewed against published agency rules
Found at Seneca No. 1 Shaft
Each name opens all spots that produce that material; the encyclopedia link opens the full ID and field guide.
Nearby rockhounding spots
Other rockhounding spots within driving distance of Seneca No. 1 Shaft.
- Iroquois MineKeweenaw County, Michigan · 1 mi awayNative Copper
- Wolverine MineHoughton County, Michigan · 4 mi awayCopper, Agate
- Gratiot River County ParkKeweenaw County, Michigan · 5 mi awayFreda Sandstone, Basalt, Rhyolite
- Cliff MineKeweenaw County, Michigan · 5 mi awayCopper, Calcite, Chlorite
- Cliff NorthKeweenaw County, Michigan · 5 mi awayCopper, Calcite, Chlorite
- Calumet Waterworks ParkHoughton County, Michigan · 8 mi awayLake Superior Agate, Prehnite, Natrolite
- Central MineKeweenaw County, Michigan · 10 mi awayCopper, Chlorastrolite
- Torch Lake BeachHoughton County, Michigan · 12 mi awayFossil, Petoskey Stone
Across the state line from Seneca No. 1 Shaft
Seneca No. 1 Shaft is close enough to the Michigan border that the next-closest rockhounding spots are in a neighboring state. Worth knowing if you are already on the road.
Seneca No. 1 Shaft FAQ
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More rockhounding in Michigan
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