Marfa and Ft. Davis: Agate & Chalcedony Rockhounding in Jeff Davis County, Texas

Updated June 2026

Marfa and Ft. Davis is a mapped rockhounding spot in Jeff Davis County, Texas. Reported finds include agate, chalcedony, jasper. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Jeff Davis County
State: Texas
Nearest road: TX 17
Coordinates: 30.45114, -103.98211

Geology at Marfa and Ft. Davis

This spot sits on Jones Basalt, mapped as basalt that formed roughly 34 to 23 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: Jones Basalt
Age: 34–23 Ma (Oligocene)
Rock types: basalt
Elevation: 5,240 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 Marfa and Ft. Davis

Conditions here are workable year-round, with typical highs from 58°F in winter to 88°F in summer.

Climate normals: NOAA 1991-2020 monthlies, MARFA 3W station (11 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 Marfa and Ft. Davis

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 Marfa and Ft. Davis.

Marfa and Ft. Davis FAQ

Where is Marfa and Ft. Davis?+

Marfa and Ft. Davis is in Jeff Davis County, Texas, at 30.45114, -103.98211. Nearest road: TX 17.

What rocks and minerals can you find at Marfa and Ft. Davis?+

Marfa and Ft. Davis is reported to produce Agate, Chalcedony, Jasper.

Is collecting allowed at Marfa and Ft. Davis?+

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 Marfa and Ft. Davis?+

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 Marfa and Ft. Davis?+

Marfa and Ft. Davis is workable year-round.

How do I get to Marfa and Ft. Davis?+

Open the directions link to navigate to 30.45114, -103.98211 in Google Maps. The nearest road is TX 17.

More rockhounding in Texas

See all 94 Texas spots →

Open Marfa and Ft. Davis on the map

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