Best spot

Challis: Red Agate & Banded Opal Rockhounding in Custer County, Idaho

Updated June 2026

Challis represents the Challis Volcanics better than a single protected petrified-forest stop, with Idaho Department of Lands listing nearby red agate, banded opal, and petrified-wood localities in Custer County. Mindat records opal from the Challis area and documents agate collecting in the same volcanic province, which makes it a practical tenth pick for silica collectors. Reported finds include red agate, banded opal. Below: coordinates, access notes, nearby spots, and trip-planning links.

Challis photos

Public image records connected to this spot or its reported material.

3 photos

Quick details

Access: Public area
County: Custer County
State: Idaho
Nearest road: Garden Creek Road
Coordinates: 44.49401, -114.29990

Geology at Challis

This spot sits on Challis Volcanics, dacitic and rhyodacitic lava, mapped as dacite that formed roughly 56 to 34 million years ago. Volcanic ground like this is where agate, jasper, and other chalcedony typically form, filling old gas pockets and fracture seams in the flow rock.

Mapped unit: Challis Volcanics, dacitic and rhyodacitic lava
Age: 56–34 Ma (Eocene)
Rock types: dacite
Elevation: 5,910 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 Challis

Best months: March to October. Typical highs run 84°F in midsummer and 26°F in midwinter, with winter lows near 8°F.

Climate normals: NOAA 1991-2020 monthlies, CHALLIS AP station (5 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.

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 Challis

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 Challis.

Challis FAQ

Where is Challis?+

Challis is in Custer County, Idaho, at 44.49401, -114.29990. Nearest road: Garden Creek Road.

What rocks and minerals can you find at Challis?+

Challis is reported to produce Red Agate, Banded Opal.

Is collecting allowed at Challis?+

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 Challis?+

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 Challis?+

The most comfortable months at Challis are March to October.

How do I get to Challis?+

Open the directions link to navigate to 44.49401, -114.29990 in Google Maps. The nearest road is Garden Creek Road.

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