Camp Crook: Moss Agate & Chalcedony Rockhounding in Harding County, South Dakota
Updated June 2026
The far northwestern corner of South Dakota around Camp Crook produces prairie moss agate and chalcedony in the river gravels of the Little Missouri system, material comparable in style to the well-known Montana moss agate. This locality adds genuine geographic and material breadth well outside the Black Hills agate country. Reported finds include moss agate, chalcedony. Below: coordinates, access notes, nearby spots, and trip-planning links.
Camp Crook photos
Public image records connected to this spot or its reported material.
Map showing Camp Crook in Harding County, South Dakota
Quick details
- Access
- Public area
- County
- Harding County
- State
- South Dakota
- Nearest road
- SD Highway 20
- Coordinates
- 45.55254, -103.96500
Geology at Camp Crook
This spot sits on Alluvium, mapped as coarse alluvium and fine alluvium that formed within roughly the last 3 million years. Gravels like these concentrate whatever survives the river: agate, jasper, and other tough silica typically show up as rounded, waxy stones.
- Mapped unit
- Alluvium
- Age
- 3 Ma to present (Quaternary)
- Rock types
- coarse alluvium and fine alluvium
- Elevation
- 3,110 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 Camp Crook
Best months: March to November. Typical highs run 88°F in midsummer and 34°F in midwinter, with winter lows near 11°F.
Climate normals: NOAA 1991-2020 monthlies, CAMP CROOK station (1 mi away).
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 Camp Crook
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 Camp Crook.
- Whitewood CreekTop pick in South DakotaLawrence County, South Dakota · 72 mi awayAmethyst, Geode, Chalcedony
- Fox RidgeMeade County, South Dakota · 80 mi awayMoss Agate
- Broken Boot Gold MineLawrence County, South Dakota · 82 mi awayGold, Arsenopyrite, Galena
- SavoyLawrence County, South Dakota · 82 mi awayGold, Fluorite, Silver
- Spearfish CanyonTop pick in South DakotaLawrence County, South Dakota · 83 mi awayAmethyst, Geode, Chalcedony
- PiedmontMeade County, South Dakota · 96 mi awaySelenite
- SummersetMeade County, South Dakota · 98 mi awayFossils
- Meade CountyMeade County, South Dakota · 99 mi awayYellow Barite, Amber Barite, Whewellite
Across the state line from Camp Crook
Camp Crook 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.
Camp Crook FAQ
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More rockhounding in South Dakota
See all 43 South Dakota spots →Open Camp Crook on the map
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