Seven Devils Mining District: Epidote & Red Garnet Rockhounding in Adams County, Idaho

Plan your visit

Generally open to casual rockhounding

County

Adams County

State

Idaho

Nearest road

National Forest Development Road 493

Coordinates

45.16617, -116.64885

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: Remote Payette National Forest mining district. Check public land and claim status, stay out of underground workings, and expect rough seasonal roads.

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 Seven Devils Mining District

Comfortable months (45 to 90°F highs)

Best months: April to October. Typical highs run 75°F in midsummer and 26°F in midwinter, with winter lows near 10°F.

Climate normals: NOAA 1991-2020 monthlies, RIGGINS station (18 mi away), adjusted for elevation.

Geology at Seven Devils Mining District

This spot sits on Blue Mountains island arc, quartz diorite and tonalite, mapped as hornblende quartz diorite and tonalite that formed roughly 145 to 66 million years ago. Plutonic rock like this weathers slowly into grus and boulders, and the most productive collecting is typically in weathered zones and drainages.

Mapped unit

Blue Mountains island arc, quartz diorite and tonalite

Age

145–66 Ma (Cretaceous)

Rock types

hornblende quartz diorite and tonalite

Elevation

6,840 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

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