Spearfish Canyon: Geode Digging in Lawrence County, South Dakota

Plan your visit

Generally open to casual rockhounding

County

Lawrence County

State

South Dakota

Nearest road

US Highway 14A

Coordinates

44.34701, -103.92440

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: Spearfish Canyon lies on the northern edge of Black Hills National Forest along the US-14A scenic byway, where personal-use surface collecting of rocks and minerals (including geodes and chalcedony) is allowed without a permit. Collecting must be from the surface, not by digging into banks, and fossils are off limits. Collectors should avoid private inholdings and developed recreation sites along the byway. BLM records active mining claims in this area. Collecting from inside an active claim needs the claim holder's permission.

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 Spearfish Canyon

Comfortable months (45 to 90°F highs)

Best months: March to November. Typical highs run 82°F in midsummer and 38°F in midwinter, with winter lows near 18°F.

Climate normals: NOAA 1991-2020 monthlies, LEAD station (9 mi away).

Geology at Spearfish Canyon

This spot sits on ground mapped as Deadwood Formation that formed roughly 495 to 470 million years ago. Geodes typically weather free of their host rock and collect as rounded float in soils and drainages.

Mapped unit

Deadwood Formation

Age

495–470 Ma (Late Cambrian to Early Ordovician)

Elevation

5,060 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.

• BLM Montana-Dakotas rockhounding rules
• Buffalo Gap National Grassland
• South Dakota Geological Survey
• Community submissions reviewed against published agency rules