Big Lost River: Geode Digging in Butte County, Idaho

Updated July 2026

Big Lost River is a mapped rockhounding spot in Butte County, Idaho. Reported finds include geode, amethyst. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Permission required
County: Butte County
State: Idaho
Coordinates: 43.79522, -112.85184

Geology at Big Lost River

This spot sits on Fluvial and lake sediment, mapped as fine alluvium that formed within roughly the last 3 million years. Geodes weather out of their host rock and collect in gravels like these, where their round shape and light heft help them stand out.

Mapped unit: Fluvial and lake sediment
Age: 3 Ma to present (Quaternary)
Rock types: fine alluvium
Elevation: 4,780 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 Big Lost River

Best months: March to October. Typical highs run 88°F in midsummer and 30°F in midwinter, with winter lows near 7°F.

Climate normals: NOAA 1991-2020 monthlies, HOWE station (8 mi away).

Land & collecting status

Permission required before collecting

Requires landowner or agency permission before any collecting. Do not enter without explicit authorization.

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

Idaho Panhandle National Forests — Emerald Creek
Idaho Geological Survey
Spencer Opal Mines (fee-dig operator)
Community submissions reviewed against published agency rules

Found at Big Lost River

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 Big Lost River.

Big Lost River FAQ

Where is Big Lost River?+

Big Lost River is in Butte County, Idaho, at 43.79522, -112.85184.

What rocks and minerals can you find at Big Lost River?+

Big Lost River is reported to produce Geode, Amethyst.

Is collecting allowed at Big Lost River?+

Permission required before collecting. Requires landowner or agency permission before any collecting. Do not enter without explicit authorization. Always confirm current rules with the managing agency before a trip.

What tools should I bring to Big Lost River?+

Bring a crack hammer, a chisel, safety glasses, and a bucket. Candidates are rounder and lighter than solid rock; a soil pipe cutter opens them cleaner than a flat smash.

When is the best time to visit Big Lost River?+

The most comfortable months at Big Lost River are March to October.

How do I get to Big Lost River?+

Open the directions link to navigate to 43.79522, -112.85184 in Google Maps. Some spots are remote, so check road conditions before driving out.

More rockhounding in Idaho

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Open Big Lost River on the map

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