Where to Find Chalcedony in Texas

Texas chalcedony tracks the same Trans-Pecos volcanic belt that produces the state's agate. Brewster and Presidio counties yield red, pink, and white chalcedony in the Tascotal and Mitchell Mesa tuffs, often as nodule rinds on plume agate. Marfa-area chalcedony runs softer and pinker; Big Bend chalcedony is harder and more saturated. Smaller showings of milky and gray chalcedony turn up in the Llano uplift of central Texas. Most ground is on private ranches that run dig days; trespass on Texas ranchland is prosecuted aggressively. Coastal Texas adds occasional chalcedony beach pebbles along the Padre Island shoreline. The most productive ground is in Woodward Ranch (Brewster County), Marfa volcanics (Presidio County), Llano uplift (Mason County).

Casual hand collection of common rocks and minerals like chalcedony is allowed on most BLM and U.S. Forest Service land in Texas, with daily and annual limits set by the local field office. National parks, most state parks, and tribal land are off-limits. Always confirm rules before a trip.

Woodward Ranch (Brewster County) is the standout. Other strong ground includes Marfa volcanics (Presidio County), Llano uplift (Mason County).