La Grange: Agate & Chalcedony Rockhounding in Lewis County, Missouri

Plan your visit

Generally open to casual rockhounding

County

Lewis County

State

Missouri

Nearest road

Wharf Street

Postcode

63448

Coordinates

40.04691, -91.49584

Coordinates are approximate. Confirm the exact ground in the RockHoundR app, where land overlays show which agency manages the area.

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.

Access note: Collect from Mississippi River gravel bars and sandbars below the high-water mark, which are open to the public on this navigable waterway. Public river access and boat ramps near La Grange provide legal entry; stay below the high-water mark and off adjacent private land and any commercial gravel-pit property. Surface collecting by hand only.

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.

Best time to visit La Grange

Comfortable months (45 to 90°F highs)

Best months: March to November. Typical highs run 85°F in midsummer and 33°F in midwinter, with winter lows near 17°F.

Climate normals: NOAA 1991-2020 monthlies, CANTON L&D 20 station (7 mi away).

Geology at La Grange

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

490 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.

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.

• Missouri Geological Survey
• Mark Twain National Forest
• Missouri State Parks rules
• Community submissions reviewed against published agency rules