Agate: Agate & Chalcedony Rockhounding in Grand County, Utah

Plan your visit

Generally open to casual rockhounding

County

Grand County

State

Utah

Nearest road

CR 179

Coordinates

39.01757, -109.24721

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.

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 Agate

Comfortable months (45 to 90°F highs)

Best months: September to June. Typical highs run 95°F in midsummer and 46°F in midwinter, with winter lows near 19°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, GLADE PARK 17W station (11 mi away), adjusted for elevation.

Geology at Agate

This spot sits on ground mapped as Salt Wash Sandstone Member of Morrison Formation that formed roughly 160 to 145 million years ago. Petrified wood typically comes from volcanic ash beds like the ones associated with this ground, where buried forests were slowly replaced by silica.

Mapped unit

Salt Wash Sandstone Member of Morrison Formation

Age

160–145 Ma (Late Jurassic)

Elevation

4,370 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

• BLM Utah, Rockhounding overview
• Utah Geological Survey, collecting guidelines
• SITLA, surface use rules
• Community submissions reviewed against published agency rules