Missouri River: Cassiterite & Chalcedony Rockhounding in Lewis and Clark County, Montana

Plan your visit

Generally open to casual rockhounding

County

Lewis and Clark County

State

Montana

Nearest road

Danas Point Drive

Coordinates

46.72837, -111.87461

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: BLM records active mining claims in this area. Collecting from inside an active claim needs the claim holder's permission.

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 Missouri River

Comfortable months (45 to 90°F highs)

Best months: March to October. Typical highs run 87°F in midsummer and 33°F in midwinter, with winter lows near 14°F.

Climate normals: NOAA 1991-2020 monthlies, HELENA AP ASOS station (10 mi away), adjusted for elevation.

Geology at Missouri River

This spot sits on Alluvial and colluvial deposits, mapped as sand and gravel that formed within roughly the last 3 million years. Stream-worked gravels like these are where placer gold tends to concentrate, settling toward bedrock, inside gravel bars, and behind boulders.

Mapped unit

Alluvial and colluvial deposits

Age

3 Ma to present (Quaternary)

Rock types

sand and gravel

Elevation

3,670 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.

State guidance last verified: April 1, 2026

• BLM Montana, Recreational mineral collecting
• Montana Bureau of Mines and Geology
• Gem Mountain Sapphire Mine (fee-dig operator)
• Community submissions reviewed against published agency rules