Fandango Pass: Agate & Chalcedony Rockhounding in Modoc County, California

Plan your visit

Generally open to casual rockhounding

County

Modoc County

State

California

Nearest road

Fandango Pass Road

Coordinates

41.80207, -120.20678

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.

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 Fandango Pass

Comfortable months (45 to 90°F highs)

Best months: March to October. Typical highs run 81°F in midsummer and 35°F in midwinter, with winter lows near 18°F.

Climate normals: NOAA 1991-2020 monthlies, FT BIDWELL station (5 mi away), adjusted for elevation.

Geology at Fandango Pass

This spot sits on volcanic flow rocks, unit 17 (Cascade Range), mapped as andesite and basalt that formed roughly 28 to 2 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

volcanic flow rocks, unit 17 (Cascade Range)

Age

28–2 Ma (Late Oligocene to Pleistocene)

Rock types

andesite and basalt

Elevation

6,150 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 California, Recreational mineral collecting
• California Geological Survey
• CDFW, Suction Dredge Mining Permit Program
• Community submissions reviewed against published agency rules