Manitou Island: Lake Superior Agate & Quartz Rockhounding in Keweenaw County, Michigan

Public accessBest spot2 mineralsKeweenaw County, MichiganUpdated June 2026

Minerals reported: 2
Elevation: 590 ft
Best months: May to October

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.

Plan your visit

Generally open to casual rockhounding

County: Keweenaw County
State: Michigan
Postcode: 49918
Coordinates: 47.41499, -87.62794

Get directions View on Google Maps

Coordinates are approximate. Confirm the exact ground in the RockHoundR app, where land overlays show which agency manages the area.

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.

Access note: The island is reachable only by private boat across exposed, harborless water, with a small dock about half a mile west of the light and a rough trail from there. Collect within the 93-acre preserve, since the rest of the island has other ownership, and the light-station buildings are closed except by arrangement.

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 Manitou Island

23°J

25°F

34°M

44°A

58°M

67°J

73°J

74°A

66°S

52°O

39°N

29°D

Comfortable months (45 to 90°F highs)

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).

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.

Today's weather

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The app shows live weather, recent rain, and a daily rockhounding score for Manitou Island.

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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: April 1, 2026

Michigan DNR, Rockhounding rules
Michigan Geological Survey
Isle Royale National Park, Rules
Community submissions reviewed against published agency rules

Found at Manitou Island

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 Manitou Island.

Keweenaw PointKeweenaw County, Michigan · 4 mi awayKeweenaw Agate, Thomsonite, Datolite
High Rock BayKeweenaw County, Michigan · 4 mi awayPrehnite, Calcite, Copper
Keweenaw Rocket RangeKeweenaw County, Michigan · 4 mi awayGranite, Prehnite, Copper
Esrey ParkKeweenaw County, Michigan · 20 mi awayGranite, Prehnite, Copper
Central MineKeweenaw County, Michigan · 27 mi awayCopper, Chlorastrolite
Cliff MineKeweenaw County, Michigan · 32 mi awayCopper, Calcite, Chlorite
Cliff NorthKeweenaw County, Michigan · 32 mi awayCopper, Calcite, Chlorite
Iroquois MineKeweenaw County, Michigan · 35 mi awayNative Copper

Manitou Island FAQ

Where is Manitou Island?+

Manitou Island is in Keweenaw County, Michigan, at 47.41499, -87.62794.

What rocks and minerals can you find at Manitou Island?+

Manitou Island is reported to produce Lake Superior Agate, Quartz.

Is collecting allowed at Manitou Island?+

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. Always confirm current rules with the managing agency before a trip.

What tools should I bring to Manitou Island?+

Most agate and jasper is surface float: bring a spray bottle, a pick or small shovel, and a sturdy bag. Wet stones show their banding and translucence.

When is the best time to visit Manitou Island?+

The most comfortable months at Manitou Island are May to October.

How do I get to Manitou Island?+

Open the directions link to navigate to 47.41499, -87.62794 in Google Maps. Some spots are remote, so check road conditions before driving out.