Quarry Island: Lake Superior Agate Rockhounding in Dakota County, Minnesota

Updated June 2026

Quarry Island is a mapped rockhounding spot in Dakota County, Minnesota. Reported finds include lake superior agate. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Dakota County
State: Minnesota
Nearest road: I 494
Postcode: 55111
Coordinates: 44.86794, -93.18087

Geology at Quarry Island

This spot sits on ground mapped as St. Peter Sandstone that formed roughly 470 to 445 million years ago. Tough silica like agate, jasper, and chert typically weathers out of beds like these and collects as float in drainages and on deflation surfaces.

Mapped unit: St. Peter Sandstone
Age: 470–445 Ma (Middle Ordovician to Late Ordovician)
Elevation: 710 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 Quarry Island

Best months: April to October. Typical highs run 84°F in midsummer and 24°F in midwinter, with winter lows near 9°F.

Climate normals: NOAA 1991-2020 monthlies, MINNEAPOLIS-ST PAUL INTL AP station (3 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 Quarry Island

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

Lake Superior Agate Encyclopedia →

Nearby rockhounding spots

Other rockhounding spots within driving distance of Quarry Island.

Across the state line from Quarry Island

Quarry Island is close enough to the Minnesota border that the next-closest rockhounding spots are in a neighboring state. Worth knowing if you are already on the road.

Quarry Island FAQ

Where is Quarry Island?+

Quarry Island is in Dakota County, Minnesota, at 44.86794, -93.18087. Nearest road: I 494.

What rocks and minerals can you find at Quarry Island?+

Quarry Island is reported to produce Lake Superior Agate.

Is collecting allowed at Quarry Island?+

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. Always confirm current rules with the managing agency before a trip.

What tools should I bring to Quarry Island?+

Most agate and jasper is surface float: bring a spray bottle, a pick or small shovel, and a sturdy bag. Wet stones show their banding and translucence.

When is the best time to visit Quarry Island?+

The most comfortable months at Quarry Island are April to October.

How do I get to Quarry Island?+

Open the directions link to navigate to 44.86794, -93.18087 in Google Maps. The nearest road is I 494.

More rockhounding in Minnesota

See all 49 Minnesota spots →

Open Quarry Island on the map

Use the RockHoundR app for live land overlays, weather, geology, directions, and saved finds.