Llano River at Grenwelge Park: Blue Quartz & Quartz Rockhounding in Llano County, Texas

Plan your visit

Generally open to casual rockhounding

County

Llano County

State

Texas

Coordinates

30.75180, -98.67440

Coordinates are approximate. Confirm the exact ground in the RockHoundR app, where land overlays show which agency manages the area.

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.

Access note: Enter at Grenwelge Park in Llano, or nearby Robinson City Park or Badu Park, and search the gravel bars at low water. The riverbed is public, but a state permit is technically required to remove sand or gravel in quantity, so collect lightly and avoid the private banks.

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.

Best time to visit Llano River at Grenwelge Park

Comfortable months (45 to 90°F highs)

Best months: October to May. Typical highs run 96°F in midsummer and 62°F in midwinter, with winter lows near 34°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, LLANO station (1 mi away).

Geology at Llano River at Grenwelge Park

This spot sits on Younger granitic intrusion, mapped as hypabyssal felsic alkaline that formed roughly 2500 to 540 million years ago. Granitic ground like this typically carries quartz veins and pockets, and weathered crystals tend to collect in the soils and drainages below.

Mapped unit

Younger granitic intrusion

Age

2500–540 Ma (Proterozoic)

Rock types

hypabyssal felsic alkaline

Elevation

1,010 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.

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