Rio Grande River Area: Agate & Agatized Wood Rockhounding in Webb County, Texas

Updated June 2026

Rio Grande River Area is a mapped rockhounding spot in Webb County, Texas. Reported finds include agate, agatized wood, chalcedony, jasper. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Webb County
State: Texas
Nearest road: Rio Grande Vega Trail
Postcode: 78040
Coordinates: 27.49789, -99.49218

Geology at Rio Grande River Area

This spot sits on ground mapped as Alluvium, undivided 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: Alluvium, undivided
Age: 3 Ma to present (Pleistocene to Holocene)
Elevation: 370 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 Rio Grande River Area

Best months: October to April. Typical highs run 100°F in midsummer and 69°F in midwinter, with winter lows near 47°F. Summer heat here is intense, so carry more water than you think you need and work the early morning.

Climate normals: NOAA 1991-2020 monthlies, LAREDO INTL AP station (3 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

Texas Parks and Wildlife Department
Bureau of Economic Geology — Texas geology
Big Bend National Park — Rules
Community submissions reviewed against published agency rules

Found at Rio Grande River Area

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 Rio Grande River Area.

Rio Grande River Area FAQ

Where is Rio Grande River Area?+

Rio Grande River Area is in Webb County, Texas, at 27.49789, -99.49218. Nearest road: Rio Grande Vega Trail.

What rocks and minerals can you find at Rio Grande River Area?+

Rio Grande River Area is reported to produce Agate, Agatized Wood, Chalcedony, Jasper.

Is collecting allowed at Rio Grande River Area?+

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 Rio Grande River Area?+

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 Rio Grande River Area?+

The most comfortable months at Rio Grande River Area are October to April. Summer heat here is intense, so carry more water than you think you need and work the early morning.

How do I get to Rio Grande River Area?+

Open the directions link to navigate to 27.49789, -99.49218 in Google Maps. The nearest road is Rio Grande Vega Trail.

More rockhounding in Texas

See all 94 Texas spots →

Open Rio Grande River Area on the map

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