Rattlesnake Mt.: Petrified Wood & Opalized Wood Rockhounding in Benton County, Washington

Updated June 2026

Rattlesnake Mt. is a mapped rockhounding spot in Benton County, Washington. Reported finds include petrified wood, opalized wood. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Benton County
State: Washington
Coordinates: 46.39571, -119.61312

Geology at Rattlesnake Mt.

This spot sits on Pomona Member, Saddle Mountains Basalt, mapped as basalt flows (pomona member [crb and smb]) 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: Pomona Member, Saddle Mountains Basalt
Age: 23–5 Ma (Miocene)
Rock types: basalt flows (pomona member [crb and smb])
Elevation: 3,020 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 Rattlesnake Mt.

Best months: March to October. Typical highs run 83°F in midsummer and 32°F in midwinter, with winter lows near 19°F.

Climate normals: NOAA 1991-2020 monthlies, PROSSER station (15 mi away), adjusted for elevation.

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 Rattlesnake Mt.

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 Rattlesnake Mt..

Across the state line from Rattlesnake Mt.

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

Rattlesnake Mt. FAQ

Where is Rattlesnake Mt.?+

Rattlesnake Mt. is in Benton County, Washington, at 46.39571, -119.61312.

What rocks and minerals can you find at Rattlesnake Mt.?+

Rattlesnake Mt. is reported to produce Petrified Wood, Opalized Wood.

Is collecting allowed at Rattlesnake Mt.?+

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 Rattlesnake Mt.?+

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 Rattlesnake Mt.?+

The most comfortable months at Rattlesnake Mt. are March to October.

How do I get to Rattlesnake Mt.?+

Open the directions link to navigate to 46.39571, -119.61312 in Google Maps. Some spots are remote, so check road conditions before driving out.

More rockhounding in Washington

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Open Rattlesnake Mt. on the map

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