Antrim Creek Natural Area: Petoskey Stone & Charlevoix Stone Rockhounding in Antrim County, Michigan

Updated August 2026

Antrim Creek Natural Area is a mapped rockhounding spot in Antrim County, Michigan. Reported finds include petoskey stone, charlevoix stone, horn coral, fossils, chain coral, and more. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Antrim County
State: Michigan
Postcode: 49729
Coordinates: 45.17907, -85.37866

Geology at Antrim Creek Natural Area

This spot sits on Antrim Shale, mapped as black shale that formed roughly 385 to 360 million years ago. Sedimentary layers like these are where fossils are typically preserved, and fresh exposures after rain or in active cuts tend to produce best.

Mapped unit: Antrim Shale
Age: 385–360 Ma (Late Devonian)
Rock types: black shale
Elevation: 610 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 Antrim Creek Natural Area

Best months: April to November. Typical highs run 76°F in midsummer and 29°F in midwinter, with winter lows near 17°F.

Climate normals: NOAA 1991-2020 monthlies, CHARLEVOIX station (11 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: April 1, 2026

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

Found at Antrim Creek Natural Area

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 Antrim Creek Natural Area.

Antrim Creek Natural Area FAQ

Where is Antrim Creek Natural Area?+

Antrim Creek Natural Area is in Antrim County, Michigan, at 45.17907, -85.37866.

What rocks and minerals can you find at Antrim Creek Natural Area?+

Antrim Creek Natural Area is reported to produce Petoskey Stone, Charlevoix Stone, Horn Coral, Fossils, Chain Coral, Beach Glass.

Is collecting allowed at Antrim Creek Natural Area?+

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 Antrim Creek Natural Area?+

A rock hammer, a cold chisel, safety glasses, and newspaper or foam for wrapping finds cover most fossil ground. A trowel and a sieve help in soft exposures.

When is the best time to visit Antrim Creek Natural Area?+

The most comfortable months at Antrim Creek Natural Area are April to November.

How do I get to Antrim Creek Natural Area?+

Open the directions link to navigate to 45.17907, -85.37866 in Google Maps. Some spots are remote, so check road conditions before driving out.

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Open Antrim Creek Natural Area on the map

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