Manitou Island: Lake Superior Agate & Quartz Rockhounding in Keweenaw County, Michigan
Updated June 2026
The 93-acre Manitou Island Light Station Preserve, owned by the Keweenaw Land Trust off the tip of the Keweenaw, is one of the few outer-island shores expressly open to the public for rock collecting. Its rocky Lake Superior shoreline yields Lake Superior agates and includes a visible quartz vein. The land trust acquired the preserve from the federal government in 2004. Reported finds include lake superior agate, quartz. Below: coordinates, access notes, nearby spots, and trip-planning links.
Manitou Island photos
Public image records connected to this spot or its reported material.
Map showing Manitou Island in Keweenaw County, Michigan
Quick details
- Access
- Public area
- County
- Keweenaw County
- State
- Michigan
- Postcode
- 49918
- Coordinates
- 47.41499, -87.62794
Geology at Manitou Island
This spot sits on Copper Harbor Conglomerate, mapped as conglomerate and sandstone that formed roughly 1600 to 1000 million years ago. Tough silica like agate, jasper, and chert typically weathers out of beds like these and collects as float in drainages and on deflation surfaces.
- Mapped unit
- Copper Harbor Conglomerate
- Age
- 1600–1000 Ma (Mesoproterozoic)
- Rock types
- conglomerate and sandstone
- Elevation
- 590 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.
Best time to visit Manitou Island
Best months: May to October. Typical highs run 73°F in midsummer and 23°F in midwinter, with winter lows near 11°F.
Climate normals: NOAA 1991-2020 monthlies, COPPER HARBOR FT WILKINS station (12 mi away).
Land & collecting status
Generally open to casual rockhounding
Most public-tagged spots sit on BLM, U.S. Forest Service, or other federal land where reasonable hand collecting of common rocks and minerals is allowed. Confirm posted rules and active mining claims before you dig.
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.
Sources & 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 Manitou Island
Each chip 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 Manitou Island.
- Keweenaw PointTop pick in MichiganKeweenaw County, Michigan · 4 mi awayKeweenaw Agate, Thomsonite, Datolite
- High Rock BayKeweenaw County, Michigan · 4 mi awayPrehnite, Calcite, Copper
- Cliff MineKeweenaw County, Michigan · 32 mi awayCopper, Calcite, Chlorite
- Cliff NorthKeweenaw County, Michigan · 32 mi awayCopper, Calcite, Chlorite
- Gratiot River County ParkKeweenaw County, Michigan · 39 mi awayFreda Sandstone, Basalt, Rhyolite
- Torch Lake BeachHoughton County, Michigan · 43 mi awayFossils, Petoskey Stones
- Calumet Waterworks ParkHoughton County, Michigan · 43 mi awayLake Superior Agate, Prehnite, Natrolite
- McClain State ParkHoughton County, Michigan · 48 mi awayAdularia, Chalcedony, Chert
Manitou Island FAQ
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More rockhounding in Michigan
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