General Area: Moss Agate & Plume Agate Rockhounding in Brewster County, Texas

Updated June 2026

General Area is a mapped rockhounding spot in Brewster County, Texas. Reported finds include moss agate, plume agate, chalcedony, jasper, quartz. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Brewster County
State: Texas
Nearest road: Calamity Creek Road
Coordinates: 30.16759, -103.59482

Geology at General Area

This spot sits on Duff Formation (with Decie Member from Paisano caldera shown separately), Cottonwood Springs Basalt, Potato Hill Andesite, Sheep Canyon Basalt, Crossen Trachyte, and Pruett Formation, undivided, mapped as rhyolite that formed roughly 38 to 28 million years ago. Volcanic ground like this is where agate, jasper, and other chalcedony typically form, filling old gas pockets and fracture seams in the flow rock.

Mapped unit: Duff Formation (with Decie Member from Paisano caldera shown separately), Cottonwood Springs Basalt, Potato Hill Andesite, Sheep Canyon Basalt, Crossen Trachyte, and Pruett Formation, undivided
Age: 38–28 Ma (Late Eocene to Early Oligocene)
Rock types: rhyolite
Elevation: 4,920 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 General Area

Best months: July to May. Typical highs run 89°F in midsummer and 59°F in midwinter, with winter lows near 30°F.

Climate normals: NOAA 1991-2020 monthlies, ALPINE 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

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 General 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 General Area.

General Area FAQ

Where is General Area?+

General Area is in Brewster County, Texas, at 30.16759, -103.59482. Nearest road: Calamity Creek Road.

What rocks and minerals can you find at General Area?+

General Area is reported to produce Moss Agate, Plume Agate, Chalcedony, Jasper, Quartz.

Is collecting allowed at General 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 General Area?+

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.

When is the best time to visit General Area?+

The most comfortable months at General Area are July to May.

How do I get to General Area?+

Open the directions link to navigate to 30.16759, -103.59482 in Google Maps. The nearest road is Calamity Creek Road.

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