Old Monroe: Lake Superior Agate & Garnet Rockhounding in Lincoln County, Missouri

Updated June 2026

Old Monroe is a mapped rockhounding spot in Lincoln County, Missouri. Reported finds include lake superior agate, garnet, staurolite. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Lincoln County
State: Missouri
Nearest road: East Sycamore Road
Postcode: 63369
Coordinates: 38.93072, -90.74314

Geology at Old Monroe

This spot sits on ground mapped as clay, silt, and sand that formed within roughly the last 12,000 years. Gravels like these concentrate whatever survives the river: agate, jasper, and other tough silica typically show up as rounded, waxy stones.

Age: < 1 Ma (Holocene)
Rock types: clay, silt, and sand
Elevation: 430 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 Old Monroe

Best months: February to November. Typical highs run 89°F in midsummer and 40°F in midwinter, with winter lows near 22°F.

Climate normals: NOAA 1991-2020 monthlies, ST PETERS 2 SE station (14 mi away), adjusted for elevation.

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 Old Monroe

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 Old Monroe.

Across the state line from Old Monroe

Old Monroe is close enough to the Missouri border that the next-closest rockhounding spots are in a neighboring state. Worth knowing if you are already on the road.

McKee CreekTop pick in IllinoisPike County, Illinois · 56 mi awayGeode, Sphalerite

Old Monroe FAQ

Where is Old Monroe?+

Old Monroe is in Lincoln County, Missouri, at 38.93072, -90.74314. Nearest road: East Sycamore Road.

What rocks and minerals can you find at Old Monroe?+

Old Monroe is reported to produce Lake Superior Agate, Garnet, Staurolite.

Is collecting allowed at Old Monroe?+

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 Old Monroe?+

Most agate and jasper is surface float: bring a spray bottle, a pick or small shovel, and a sturdy bag. Wet stones show their banding and translucence.

When is the best time to visit Old Monroe?+

The most comfortable months at Old Monroe are February to November.

How do I get to Old Monroe?+

Open the directions link to navigate to 38.93072, -90.74314 in Google Maps. The nearest road is East Sycamore Road.

More rockhounding in Missouri

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Open Old Monroe on the map

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