William C. Sterling State Park: Rockhounding in Monroe County, Michigan

Updated August 2026

William C. Sterling State Park is a mapped rockhounding spot in Monroe County, Michigan. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Paid / fee dig
County: Monroe County
State: Michigan
Coordinates: 41.92144, -83.34221

Geology at William C. Sterling State Park

This spot sits on Bass Island Dolomite, mapped as dolostone that formed roughly 425 to 420 million years ago. Carbonate rock like this dissolves and weathers readily, so fresh road cuts, quarries, and creek exposures are typically the most productive ground.

Mapped unit: Bass Island Dolomite
Age: 425–420 Ma (Ludlow to Pridoli)
Rock types: dolostone
Elevation: 570 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 William C. Sterling State Park

Best months: April to November. Typical highs run 83°F in midsummer and 32°F in midwinter, with winter lows near 18°F.

Climate normals: NOAA 1991-2020 monthlies, NEWPORT 4SSE station (4 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 William C. Sterling State Park.

Across the state line from William C. Sterling State Park

William C. Sterling 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.

William C. Sterling State Park FAQ

Where is William C. Sterling State Park?+

William C. Sterling State Park is in Monroe County, Michigan, at 41.92144, -83.34221.

What rocks and minerals can you find at William C. Sterling State Park?+

William C. Sterling 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 William C. Sterling 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 William C. Sterling 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 William C. Sterling State Park?+

The most comfortable months at William C. Sterling State Park are April to November.

How do I get to William C. Sterling State Park?+

Open the directions link to navigate to 41.92144, -83.34221 in Google Maps. Some spots are remote, so check road conditions before driving out.

More rockhounding in Michigan

See all 107 Michigan spots →

Open William C. Sterling State Park on the map

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