Rockhounding Map & Sites in Texas: 547 Locations for Crystal Hunting, Gem Mining & More

Texas designated blue topaz as its state gemstone in 1969. The Mason County area of the central Texas Hill Country is the primary source — topaz occurs in the rhyolite (Precambrian) of the Llano Uplift. Crystals are found loose in stream gravels and in pockets within the weathered rhyolite. Colors include colorless, pale blue, and champagne (sherry topaz).

Top sites:

• Mason County ranches — Several ranches offer fee dig access for topaz. Check with the Mason County Chamber of Commerce or local rock shops for current operations.
• Streeter area, Mason County — Topaz in rhyolite outcrops and stream gravels. Private ranch land — fee access.

Texas topaz is typically colorless to pale blue in the rough. Natural blue color is uncommon — most "London Blue" topaz on the market is irradiated. The crystals are orthorhombic prisms with a characteristic basal cleavage (one flat end). Topaz is hardness 8, glassy luster, and heavy for its size. Look for transparent, glassy stones in stream gravel — screen and sort the gravel with a classifier. The Llano Uplift granites and rhyolites also produce garnet, tourmaline, and feldspar.

Texas produces high-quality agate from multiple regions. West Texas plume agate, Dryhead agate, and the famous Texas "Blue" agate (actually gray-blue chalcedony) come from the volcanic rocks of the Trans-Pecos region. South Texas produces agate from the Rio Grande gravels — the Laredo and Webb County areas produce moss agate and banded agate.

Top sites:

• Alpine/Marfa area, Brewster and Presidio counties — Plume agate, moss agate, and jasper on BLM and ranch land. The volcanic terranes of the Trans-Pecos produce diverse siliceous material.
• Rio Grande gravel bars, Webb/Zapata counties — Agate and jasper in river gravel. Public access at river crossings and recreation areas.

Texas agate is diverse — plume, moss, banded, and scenic varieties from different geological environments. The Trans-Pecos volcanic agate is the most collectible. Wet stones to evaluate patterns — agate is translucent when wet. This is excellent lapidary material. The Big Bend region of west Texas produces the finest agate but is also remote and hot. Carry extra water.

Texas has abundant petrified wood, designated as the state stone. The Eocene-age Catahoula and Manning Formations of east Texas produce silicified wood — primarily palmwood (the same formation as Louisiana's palmwood). The Trans-Pecos region produces petrified wood from different source rocks in volcanic terranes.

Top sites:

• Woodville area, Tyler County — Petrified palmwood in the Catahoula Formation. Creek gravels and road cuts. Private land — ask permission.
• Lake Livingston area, Trinity County — Petrified wood in lake shore gravel and surrounding forests.

Texas petrified palmwood shows the characteristic dot pattern (vascular bundles) in cross-section. Colors are brown, tan, red, and gray. The east Texas material is typically excellent lapidary stock — dense, well-silicified, and takes a high polish. Look for dense, heavy stones in creek gravels. Petrified wood is heavier than unsilicified wood and has a glassy fracture.