Grand Mere State Park: Rockhounding in Berrien County, Michigan

Updated August 2026

Grand Mere State Park is a mapped rockhounding spot in Berrien County, Michigan. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Paid / fee dig
County: Berrien County
State: Michigan
Postcode: 49127
Coordinates: 42.00310, -86.53682

Geology at Grand Mere State Park

This spot sits on Antrim Shale, mapped as black shale that formed roughly 385 to 360 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: Antrim Shale
Age: 385–360 Ma (Late Devonian)
Rock types: black shale
Elevation: 600 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 Grand Mere State Park

Best months: March to November. Typical highs run 83°F in midsummer and 33°F in midwinter, with winter lows near 20°F.

Climate normals: NOAA 1991-2020 monthlies, BENTON HARBOR AP station (10 mi away).

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 Grand Mere State Park.

Across the state line from Grand Mere State Park

Grand Mere State Park 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.

Grand Mere State Park FAQ

Where is Grand Mere State Park?+

Grand Mere State Park is in Berrien County, Michigan, at 42.00310, -86.53682.

What rocks and minerals can you find at Grand Mere State Park?+

Grand Mere State Park 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 Grand Mere State Park?+

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 Grand Mere State Park?+

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 Grand Mere State Park?+

The most comfortable months at Grand Mere State Park are March to November.

How do I get to Grand Mere State Park?+

Open the directions link to navigate to 42.00310, -86.53682 in Google Maps. Some spots are remote, so check road conditions before driving out.

More rockhounding in Michigan

See all 107 Michigan spots →

Open Grand Mere State Park on the map

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