Keystone: Tourmaline & Spodumene Rockhounding in Pennington County, South Dakota
- Minerals reported
- 8
- Elevation
- 4,350 ft
- Best months
- March to November
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.
Plan your visit
Generally open to casual rockhounding
- County
- Pennington County
- State
- South Dakota
- Nearest road
- Blair Street
- Postcode
- 57751
- Coordinates
- 43.89498, -103.41734
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: 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 Keystone
Comfortable months (45 to 90°F highs)
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.
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.
Today's weather
Is today a good day to go?
The app shows live weather, recent rain, and a daily rockhounding score for Keystone.
Get the appSources & 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
Found at Keystone
Each name 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.
- November MineCuster County, South Dakota · 7 mi awayArsenopyrite, Fluorapatite
- FairburnCuster County, South Dakota · 9 mi awayFairburn Agate
- Hill CityPennington County, South Dakota · 9 mi awayBeryl, Red Cassiterite, Cervantite
- Laughing Water CreekCuster County, South Dakota · 11 mi awayColumbite, Gold, Silver
- Tin MountainCuster County, South Dakota · 18 mi awayFluorapatite, Quartz, Almandine Garnet
- SummersetMeade County, South Dakota · 22 mi awayFossil
- RochfordPennington County, South Dakota · 23 mi awayArsenopyrite, Galena, Gold
- PiedmontMeade County, South Dakota · 23 mi awaySelenite
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.
- NewcastleWeston County, Wyoming · 35 mi awayGypsum
- Black Hills National ForestCrook County, Wyoming · 46 mi awayFluorite, Gold
- Warren PeakCrook County, Wyoming · 65 mi awayAzurite, Malachite
- Copper Prince MineCrook County, Wyoming · 67 mi awayChrysocolla, Gold, Malachite
- OrellaDawes County, Nebraska · 68 mi awayFairburn Agate, Jasper, Carnelian
- MontroseSioux County, Nebraska · 69 mi awayAgate, Jasper, Fossil
Keystone FAQ
Where is Keystone?+
What rocks and minerals can you find at Keystone?+
Is collecting allowed at Keystone?+
What tools should I bring to Keystone?+
When is the best time to visit Keystone?+
How do I get to Keystone?+
More rockhounding in South Dakota
See all 47 South Dakota spots →
Open Keystone on the map
Use the RockHoundR app for live land overlays, weather, geology, directions, and saved finds.
