W side of Glass Mountains: Moss Agate & Plume Agate Rockhounding in Brewster County, Texas

Updated June 2026

W side of Glass Mountains 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
Coordinates: 30.37043, -103.40020

Geology at W side of Glass Mountains

This spot sits on Capitan Formation, mapped as limestone and dolostone that formed roughly 300 to 250 million years ago. Chert and agate nodules typically form inside carbonate rock like this and weather out as tough, waxy lumps in soils and creek beds.

Mapped unit: Capitan Formation
Age: 300–250 Ma (Permian)
Rock types: limestone and dolostone
Elevation: 4,520 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 W side of Glass Mountains

Conditions here are workable year-round, with typical highs from 60°F in winter to 89°F in summer.

Climate normals: NOAA 1991-2020 monthlies, MARATHON station (14 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 W side of Glass Mountains

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 W side of Glass Mountains.

W side of Glass Mountains FAQ

Where is W side of Glass Mountains?+

W side of Glass Mountains is in Brewster County, Texas, at 30.37043, -103.40020.

What rocks and minerals can you find at W side of Glass Mountains?+

W side of Glass Mountains is reported to produce Moss Agate, Plume Agate, Chalcedony, Jasper, Quartz.

Is collecting allowed at W side of Glass Mountains?+

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 W side of Glass Mountains?+

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 W side of Glass Mountains?+

W side of Glass Mountains is workable year-round.

How do I get to W side of Glass Mountains?+

Open the directions link to navigate to 30.37043, -103.40020 in Google Maps. Some spots are remote, so check road conditions before driving out.

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Open W side of Glass Mountains on the map

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