Gull Rock: Lake Superior Agate Rockhounding in Lake County, Minnesota

Quick details

Access

Public area

County

Lake County

State

Minnesota

Nearest road

Gitchi-Gami State Trail

Coordinates

47.21823, -91.35030

Geology at Gull Rock

This spot sits on Diabase and ferrodiorite, mapped as mafic hypabyssal and diorite that formed roughly 1200 to 1000 million years ago. Plutonic rock like this weathers slowly into grus and boulders, and the most productive collecting is typically in weathered zones and drainages.

Mapped unit

Diabase and ferrodiorite

Age

1200–1000 Ma (Mesoproterozoic)

Rock types

mafic hypabyssal and diorite

Elevation

600 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 Gull Rock

Best months: April to October. Typical highs run 79°F in midsummer and 22°F in midwinter, with winter lows near 4°F.

Climate normals: NOAA 1991-2020 monthlies, WOLF RIDGE ELC station (13 mi away), adjusted for elevation.

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 Gull Rock

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

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