Dubuque: Lake Superior Agate & Moss Agate Rockhounding in Dubuque County, Iowa

Updated June 2026

Dubuque is a mapped rockhounding spot in Dubuque County, Iowa. Reported finds include lake superior agate, moss agate, oolitic agates, moonstone, jasper, and more. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Permission required
County: Dubuque County
State: Iowa
Nearest road: Riverside Road
Postcode: 52001
Coordinates: 42.57616, -90.68239

Geology at Dubuque

This spot sits on ground mapped as St. Peter Sandstone & Prairie du Chien Group that formed roughly 485 to 470 million years ago. Sedimentary beds like these are the typical host for petrified and silicified wood, which weathers out as durable float on slopes and in washes.

Mapped unit: St. Peter Sandstone & Prairie du Chien Group
Age: 485–470 Ma (Early Ordovician)
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 Dubuque

Best months: March to November. Typical highs run 85°F in midsummer and 28°F in midwinter, with winter lows near 10°F.

Climate normals: NOAA 1991-2020 monthlies, DUBUQUE L&D 11 station (3 mi away).

Land & collecting status

Permission required before collecting

Requires landowner or agency permission before any collecting. Do not enter without explicit authorization.

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 Dubuque

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

Nearby rockhounding spots

Other rockhounding spots within driving distance of Dubuque.

Across the state line from Dubuque

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

Dubuque FAQ

Where is Dubuque?+

Dubuque is in Dubuque County, Iowa, at 42.57616, -90.68239. Nearest road: Riverside Road.

What rocks and minerals can you find at Dubuque?+

Dubuque is reported to produce Lake Superior Agate, Moss Agate, Oolitic Agates, Moonstone, Jasper, Petrified Wood, Fossils.

Is collecting allowed at Dubuque?+

Permission required before collecting. Requires landowner or agency permission before any collecting. Do not enter without explicit authorization. Always confirm current rules with the managing agency before a trip.

What tools should I bring to Dubuque?+

A rock hammer, sturdy gloves, and a padded bag cover petrified wood hunting. Most pieces are surface float, so walking slopes and washes beats digging.

When is the best time to visit Dubuque?+

The most comfortable months at Dubuque are March to November.

How do I get to Dubuque?+

Open the directions link to navigate to 42.57616, -90.68239 in Google Maps. The nearest road is Riverside Road.

More rockhounding in Iowa

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Open Dubuque on the map

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