Mazon River — Rockhounding in Grundy County, Illinois

Mazon River is a mapped rockhounding spot in Grundy County, Illinois. Reported finds include fossils. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Grundy County
State: Illinois
Coordinates: 41.29336, -88.36670

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.

Sources: RockHoundR public spot dataset, app land overlays, and local agency review before each trip.

Found at Mazon River

Each chip opens all spots that produce that material; the encyclopedia link opens the full ID and field guide.

Fossils Encyclopedia →

Nearby rockhounding spots

Other rockhounding spots within driving distance of Mazon River.

Mazon River FAQ

Where is Mazon River?+

Mazon River is in Grundy County, Illinois, at 41.29336, -88.36670.

What rocks and minerals can you find at Mazon River?+

Mazon River is reported to produce Fossils.

Is collecting allowed at Mazon River?+

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.

How do I get to Mazon River?+

Open the directions link to navigate to 41.29336, -88.36670 in Google Maps. Some spots are remote — check road conditions before driving out.

More rockhounding in Illinois

See all 29 Illinois spots →

Open Mazon River on the map

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