Stillwater: Tripoli Rockhounding in Washington County, Minnesota

Updated July 2026

Stillwater is a mapped rockhounding spot in Washington County, Minnesota. Reported finds include tripoli. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Permission required
County: Washington County
State: Minnesota
Nearest road: Dellwood Road
Postcode: 55082
Coordinates: 45.07590, -92.81066

Geology at Stillwater

This spot sits on Tunnel City Group, mapped as sandstone and siltstone medium to very fine grained that formed roughly 495 to 485 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: Tunnel City Group
Age: 495–485 Ma (Late Cambrian)
Rock types: sandstone and siltstone medium to very fine grained
Elevation: 700 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 Stillwater

Best months: March to November. Typical highs run 85°F in midsummer and 27°F in midwinter, with winter lows near 9°F.

Climate normals: NOAA 1991-2020 monthlies, STILLWATER 1 SE station (2 mi away).

Land & collecting status

Permission required before collecting

Requires landowner or agency permission before any collecting. Do not enter without explicit authorization.

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 Stillwater

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

Tripoli

Nearby rockhounding spots

Other rockhounding spots within driving distance of Stillwater.

Across the state line from Stillwater

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

Stillwater FAQ

Where is Stillwater?+

Stillwater is in Washington County, Minnesota, at 45.07590, -92.81066. Nearest road: Dellwood Road.

What rocks and minerals can you find at Stillwater?+

Stillwater is reported to produce Tripoli.

Is collecting allowed at Stillwater?+

Permission required before collecting. Requires landowner or agency permission before any collecting. Do not enter without explicit authorization. Always confirm current rules with the managing agency before a trip.

What tools should I bring to Stillwater?+

A rock hammer, sturdy gloves, safety glasses, and a collecting bag cover the basics here. Add a spray bottle: wet rock shows color and pattern that dry rock hides.

When is the best time to visit Stillwater?+

The most comfortable months at Stillwater are March to November.

How do I get to Stillwater?+

Open the directions link to navigate to 45.07590, -92.81066 in Google Maps. The nearest road is Dellwood Road.

More rockhounding in Minnesota

See all 49 Minnesota spots →

Open Stillwater on the map

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