Keystone: Tourmaline & Spodumene Rockhounding in Pennington County, South Dakota

Updated June 2026

Keystone is a mapped rockhounding spot in Pennington County, South Dakota. Reported finds include tourmaline, spodumene, lepidolite, autunite, golden beryl, and more. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Pennington County
State: South Dakota
Nearest road: Blair Street
Postcode: 57751
Coordinates: 43.89498, -103.41734

Geology at Keystone

This spot sits on ground mapped as Metagraywacke unit 2 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: Metagraywacke unit 2
Age: 2500–1600 Ma (Paleoproterozoic)
Elevation: 4,350 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 Keystone

Best months: March to November. Typical highs run 82°F in midsummer and 40°F in midwinter, with winter lows near 22°F.

Climate normals: NOAA 1991-2020 monthlies, MT RUSHMORE NMEM station (2 mi away), adjusted for elevation.

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.

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.

Sources: RockHoundR public spot dataset, app land overlays, and local agency review before each trip.

Found at Keystone

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

Nearby rockhounding spots

Other rockhounding spots within driving distance of Keystone.

Across the state line from Keystone

Keystone is close enough to the South Dakota border that the next-closest rockhounding spots are in a neighboring state. Worth knowing if you are already on the road.

Keystone FAQ

Where is Keystone?+

Keystone is in Pennington County, South Dakota, at 43.89498, -103.41734. Nearest road: Blair Street.

What rocks and minerals can you find at Keystone?+

Keystone is reported to produce Tourmaline, Spodumene, Lepidolite, Autunite, Golden Beryl, Quartz, Zircon, Aquamarine.

Is collecting allowed at Keystone?+

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. Always confirm current rules with the managing agency before a trip.

What tools should I bring to Keystone?+

A rock hammer, a small pry bar, gloves, and safety glasses cover most crystal ground. A screen helps in loose pocket soil, and newspaper protects points on the way out.

When is the best time to visit Keystone?+

The most comfortable months at Keystone are March to November.

How do I get to Keystone?+

Open the directions link to navigate to 43.89498, -103.41734 in Google Maps. The nearest road is Blair Street.

More rockhounding in South Dakota

See all 43 South Dakota spots →

Open Keystone on the map

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