Berlin & Utley: Rhyolite Rockhounding in Green Lake County, Wisconsin

Quick details

Access

Public area

County

Green Lake County

State

Wisconsin

Nearest road

East Huron Street

Postcode

54923

Coordinates

43.96839, -88.94419

Geology at Berlin & Utley

This spot sits on Rhyolite, mapped as rhyolite and mixed clastic that formed roughly 2500 to 1600 million years ago. Volcanic ground like this weathers into rocky slopes and float, and fresh exposures in cuts and drainages are usually the most productive places to look.

Mapped unit

Rhyolite

Age

2500–1600 Ma (Paleoproterozoic)

Rock types

rhyolite and mixed clastic

Elevation

820 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 Berlin & Utley

Best months: April to October. Typical highs run 81°F in midsummer and 25°F in midwinter, with winter lows near 8°F.

Climate normals: NOAA 1991-2020 monthlies, BERLIN WWTP station (2 mi away).

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.

Sources: RockHoundR public spot dataset, app land overlays, and local agency review before each trip.

Found at Berlin & Utley

Each chip opens all spots that produce that material; the encyclopedia link opens the full ID and field guide.

• Rhyolite