Moses Coulee: Opalized Wood Rockhounding in Douglas County, Washington

Updated June 2026

Moses Coulee is a mapped rockhounding spot in Douglas County, Washington. Reported finds include opalized wood. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Douglas County
State: Washington
Coordinates: 47.45208, -119.81041

Geology at Moses Coulee

This spot sits on Frenchman Springs Member, Wanapum Basalt, mapped as basalt flows (frenchman springs member [crb and wb]) that formed roughly 23 to 5 million years ago. Petrified wood typically comes from volcanic ash beds like the ones associated with this ground, where buried forests were slowly replaced by silica.

Mapped unit: Frenchman Springs Member, Wanapum Basalt
Age: 23–5 Ma (Miocene)
Rock types: basalt flows (frenchman springs member [crb and wb])
Elevation: 1,270 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 Moses Coulee

Best months: March to November. Typical highs run 87°F in midsummer and 36°F in midwinter, with winter lows near 23°F.

Climate normals: NOAA 1991-2020 monthlies, QUINCY station (16 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

Washington Geological Survey (DNR)
Stonerose Interpretive Center — Visit & rules
BLM Spokane District
Community submissions reviewed against published agency rules

Found at Moses Coulee

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

Opalized Wood Encyclopedia →

Nearby rockhounding spots

Other rockhounding spots within driving distance of Moses Coulee.

Moses Coulee FAQ

Where is Moses Coulee?+

Moses Coulee is in Douglas County, Washington, at 47.45208, -119.81041.

What rocks and minerals can you find at Moses Coulee?+

Moses Coulee is reported to produce Opalized Wood.

Is collecting allowed at Moses Coulee?+

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 Moses Coulee?+

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 Moses Coulee?+

The most comfortable months at Moses Coulee are March to November.

How do I get to Moses Coulee?+

Open the directions link to navigate to 47.45208, -119.81041 in Google Maps. Some spots are remote, so check road conditions before driving out.

More rockhounding in Washington

See all 92 Washington spots →

Open Moses Coulee on the map

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