Terlingua: Calcite & Calomel Rockhounding in Brewster County, Texas

Updated June 2026

Terlingua is a mapped rockhounding spot in Brewster County, Texas. Reported finds include calcite, calomel, cinnabar, fluorite, mercury, and more. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Brewster County
State: Texas
Nearest road: FM 170
Coordinates: 29.30886, -103.62752

Geology at Terlingua

This spot sits on Santa Elena Limestone, Sue Peaks Formation, Del Carmen Limestone, and Telephone Canyon Formation, undivided, mapped as limestone that formed roughly 115 to 100 million years ago. Carbonate rock like this is the classic host for lead, zinc, and fluorite mineralization, which typically follows old cavities and replacement zones.

Mapped unit: Santa Elena Limestone, Sue Peaks Formation, Del Carmen Limestone, and Telephone Canyon Formation, undivided
Age: 115–100 Ma (Early Cretaceous)
Rock types: limestone
Elevation: 3,030 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 Terlingua

Best months: October to April. Typical highs run 99°F in midsummer and 64°F in midwinter, with winter lows near 32°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, TERLINGUA station (3 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 Terlingua

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 Terlingua.

Terlingua FAQ

Where is Terlingua?+

Terlingua is in Brewster County, Texas, at 29.30886, -103.62752. Nearest road: FM 170.

What rocks and minerals can you find at Terlingua?+

Terlingua is reported to produce Calcite, Calomel, Cinnabar, Fluorite, Mercury, Terlinguaite, Pompom Agate, Aragonite.

Is collecting allowed at Terlingua?+

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 Terlingua?+

A rock hammer, gloves, and safety glasses cover old mining-district ground. Stay out of shafts and adits; the best specimens typically come from dump piles.

When is the best time to visit Terlingua?+

The most comfortable months at Terlingua 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 Terlingua?+

Open the directions link to navigate to 29.30886, -103.62752 in Google Maps. The nearest road is FM 170.

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