Tin Mountain: Fluorapatite & Quartz Rockhounding in Custer County, South Dakota

Plan your visit

Confirm rules before collecting

County

Custer County

State

South Dakota

Nearest road

Warren Gulch

Coordinates

43.75574, -103.72009

Coordinates are approximate. Confirm the exact ground in the RockHoundR app, where land overlays show which agency manages the area.

Land & collecting status

Confirm rules before collecting

Land status here is not confirmed. Verify with the managing agency before collecting, federal, state, and tribal rules differ.

Access note: 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 Tin Mountain

Comfortable months (45 to 90°F highs)

Best months: April to October. Typical highs run 78°F in midsummer and 34°F in midwinter, with winter lows near 14°F.

Climate normals: NOAA 1991-2020 monthlies, CUSTER CO AP station (5 mi away), adjusted for elevation.

Geology at Tin Mountain

This spot sits on ground mapped as Distal metagraywacke that formed roughly 2500 to 1600 million years ago. Sedimentary rock like this erodes unevenly, so the most productive collecting is typically along fresh cuts, badland slopes, and active drainages.

Mapped unit

Distal metagraywacke

Age

2500–1600 Ma (Paleoproterozoic)

Elevation

5,780 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