Mann Lake Recreation Site: Agate & Thunderegg Rockhounding in Harney County, Oregon

Updated August 2026

Mann Lake Recreation Site is a mapped rockhounding spot in Harney County, Oregon. Reported finds include agate, thunderegg. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Harney County
State: Oregon
Coordinates: 42.78255, -118.44744

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 Oregon/Washington, Rockhounding & mineral material
Oregon Department of Geology and Mineral Industries (DOGAMI)
Oregon Parks and Recreation Department, beach collecting rules
Community submissions reviewed against published agency rules

Found at Mann Lake Recreation Site

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 Mann Lake Recreation Site.

Across the state line from Mann Lake Recreation Site

Mann Lake Recreation Site is close enough to the Oregon border that the next-closest rockhounding spots are in a neighboring state. Worth knowing if you are already on the road.

Mann Lake Recreation Site FAQ

Where is Mann Lake Recreation Site?+

Mann Lake Recreation Site is in Harney County, Oregon, at 42.78255, -118.44744.

What rocks and minerals can you find at Mann Lake Recreation Site?+

Mann Lake Recreation Site is reported to produce Agate, Thunderegg.

Is collecting allowed at Mann Lake Recreation Site?+

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 Mann Lake Recreation Site?+

Most agate and jasper is surface float: bring a spray bottle, a pick or small shovel, and a sturdy bag. Wet stones show their banding and translucence.

How do I get to Mann Lake Recreation Site?+

Open the directions link to navigate to 42.78255, -118.44744 in Google Maps. Some spots are remote, so check road conditions before driving out.

More rockhounding in Oregon

See all 181 Oregon spots →

Open Mann Lake Recreation Site on the map

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