Forked Horn Butte: Thundereggs Rockhounding in Crook County, Oregon

Updated June 2026

Forked Horn Butte is a mapped rockhounding spot in Crook County, Oregon. Reported finds include thundereggs. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Permission required
County: Crook County
State: Oregon
Coordinates: 44.45525, -120.56096

Geology at Forked Horn Butte

This spot sits on John Day/Clarno Group; John Day Formation, mapped as rhyolite intrusives that formed roughly 56 to 23 million years ago. Volcanic ground like this weathers into rocky slopes and float, and fresh exposures in cuts and drainages are usually the most productive places to look.

Mapped unit: John Day/Clarno Group; John Day Formation
Age: 56–23 Ma (Eocene to Oligocene)
Rock types: rhyolite intrusives
Elevation: 4,920 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 Forked Horn Butte

Best months: March to October. Typical highs run 80°F in midsummer and 36°F in midwinter, with winter lows near 18°F.

Climate normals: NOAA 1991-2020 monthlies, PRINEVILLE station (17 mi away), adjusted for elevation.

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

BLM Oregon/Washington — Rockhounding & mineral material
Oregon Department of Geology and Mineral Industries (DOGAMI)
Oregon Parks and Recreation Department — beach collecting rules
Community submissions reviewed against published agency rules

Found at Forked Horn Butte

Each chip opens all spots that produce that material; the encyclopedia link opens the full ID and field guide.

Thundereggs Encyclopedia →

Nearby rockhounding spots

Other rockhounding spots within driving distance of Forked Horn Butte.

Forked Horn Butte FAQ

Where is Forked Horn Butte?+

Forked Horn Butte is in Crook County, Oregon, at 44.45525, -120.56096.

What rocks and minerals can you find at Forked Horn Butte?+

Forked Horn Butte is reported to produce Thundereggs.

Is collecting allowed at Forked Horn Butte?+

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 Forked Horn Butte?+

A rock hammer, sturdy gloves, safety glasses, and a collecting bag cover the basics here. Add a spray bottle: wet rock shows color and pattern that dry rock hides.

When is the best time to visit Forked Horn Butte?+

The most comfortable months at Forked Horn Butte are March to October.

How do I get to Forked Horn Butte?+

Open the directions link to navigate to 44.45525, -120.56096 in Google Maps. Some spots are remote, so check road conditions before driving out.

More rockhounding in Oregon

See all 177 Oregon spots →

Open Forked Horn Butte on the map

Use the RockHoundR app for live land overlays, weather, geology, directions, and saved finds.