Union Bay Campground: Rockhounding in Ontonagon County, Michigan

Updated August 2026

Union Bay Campground is a mapped rockhounding spot in Ontonagon County, Michigan. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Paid / fee dig
County: Ontonagon County
State: Michigan
Postcode: 49971
Coordinates: 46.81990, -89.64003

Geology at Union Bay Campground

This spot sits on Copper Harbor Conglomerate, mapped as conglomerate and sandstone that formed roughly 1600 to 1000 million years ago. Sedimentary rock like this erodes unevenly, so the most productive collecting is typically along fresh cuts, badland slopes, and active drainages.

Mapped unit: Copper Harbor Conglomerate
Age: 1600–1000 Ma (Mesoproterozoic)
Rock types: conglomerate and sandstone
Elevation: 660 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 Union Bay Campground

Best months: April to October. Typical highs run 80°F in midsummer and 23°F in midwinter, with winter lows near 5°F.

Climate normals: NOAA 1991-2020 monthlies, BERGLAND DAM station (17 mi away), adjusted for elevation.

Land & collecting status

Pay-to-dig site

This is a fee-dig location. Hours, prices, and what you can keep vary by operator. Call ahead before driving out.

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: April 1, 2026

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

Nearby rockhounding spots

Other rockhounding spots within driving distance of Union Bay Campground.

Across the state line from Union Bay Campground

Union Bay Campground 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.

Union Bay Campground FAQ

Where is Union Bay Campground?+

Union Bay Campground is in Ontonagon County, Michigan, at 46.81990, -89.64003.

What rocks and minerals can you find at Union Bay Campground?+

Union Bay Campground is on the rockhounding map but no minerals are listed in our reference. Open RockHoundR to see what other rockhounds have logged.

Is collecting allowed at Union Bay Campground?+

Pay-to-dig site. This is a fee-dig location. Hours, prices, and what you can keep vary by operator. Call ahead before driving out. Always confirm current rules with the managing agency before a trip.

What tools should I bring to Union Bay Campground?+

A rock hammer, sturdy gloves, safety glasses, and a collecting bag cover the basics here. Add a spray bottle: wet rock shows color and pattern that dry rock hides.

When is the best time to visit Union Bay Campground?+

The most comfortable months at Union Bay Campground are April to October.

How do I get to Union Bay Campground?+

Open the directions link to navigate to 46.81990, -89.64003 in Google Maps. Some spots are remote, so check road conditions before driving out.

More rockhounding in Michigan

See all 107 Michigan spots →

Open Union Bay Campground on the map

Use the RockHoundR app for live land overlays, weather, geology, directions, and saved finds.