Sweetwater County: Agate & Chalcedony Rockhounding in Sweetwater County, Wyoming

Updated June 2026

Sweetwater County is a mapped rockhounding spot in Sweetwater County, Wyoming. Reported finds include agate, chalcedony, chert, jasper, petrified wood, and more. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Sweetwater County
State: Wyoming
Nearest road: WY 374
Postcode: 82935
Coordinates: 41.53876, -109.48457

Geology at Sweetwater County

This spot sits on ground mapped as Alluvial deposits that formed within roughly the last 3 million years. Petrified wood typically travels as tough float, and worked gravels like these are exactly where weathered pieces tend to collect.

Mapped unit: Alluvial deposits
Age: 3 Ma to present (Pleistocene to Holocene)
Elevation: 6,100 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 Sweetwater County

Best months: March to October. Typical highs run 87°F in midsummer and 31°F in midwinter, with winter lows near 8°F.

Climate normals: NOAA 1991-2020 monthlies, GREEN RVR station (2 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.

State guidance last verified: April 1, 2026

BLM Wyoming
Wyoming State Geological Survey
Fossil Butte National Monument
Community submissions reviewed against published agency rules

Found at Sweetwater County

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 Sweetwater County.

Across the state line from Sweetwater County

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

Sweetwater County FAQ

Where is Sweetwater County?+

Sweetwater County is in Sweetwater County, Wyoming, at 41.53876, -109.48457. Nearest road: WY 374.

What rocks and minerals can you find at Sweetwater County?+

Sweetwater County is reported to produce Agate, Chalcedony, Chert, Jasper, Petrified Wood, Silicified Wood, Quartz, Turritella Agate.

Is collecting allowed at Sweetwater County?+

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 Sweetwater County?+

A rock hammer, sturdy gloves, and a padded bag cover petrified wood hunting. Most pieces are surface float, so walking slopes and washes beats digging.

When is the best time to visit Sweetwater County?+

The most comfortable months at Sweetwater County are March to October.

How do I get to Sweetwater County?+

Open the directions link to navigate to 41.53876, -109.48457 in Google Maps. The nearest road is WY 374.

More rockhounding in Wyoming

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Open Sweetwater County on the map

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