Black Hawk County: Cold Water Agate Rockhounding in Black Hawk County, Iowa

Public accessBest spot1 mineralBlack Hawk County, IowaUpdated July 2026

Mineral reported: 1
Elevation: 910 ft
Best months: March to November

The Cedar River valley through Black Hawk County is the home ground of the Iowa coldwater agate, a pale blue-gray to cream banded agate weathered from Devonian limestone and reworked into the river gravels. It occurs alongside true Lake Superior agates carried in by glaciers, giving the local bars two distinct agate types. The Cedar River constantly refreshes its gravel, so productive ground shifts with each season. Reported finds include cold water agate. Below: coordinates, access notes, nearby spots, and trip-planning links.

Plan your visit

Generally open to casual rockhounding

County: Black Hawk County
State: Iowa
Nearest road: North Elk Run Road
Postcode: 50703
Coordinates: 42.52178, -92.25494

Get directions View on Google Maps

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.

Access note: Reach the Cedar River gravel bars from city and county river accesses such as the Cedar Bend area in Waterloo, and surface-pick below the ordinary high-water mark. Collecting is banned in George Wyth State Park upstream at Cedar Falls, so use the public non-park accesses.

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 Black Hawk County

28°J

32°F

46°M

61°A

73°M

82°J

85°J

83°A

77°S

63°O

47°N

34°D

Comfortable months (45 to 90°F highs)

Best months: March to November. Typical highs run 85°F in midsummer and 28°F in midwinter, with winter lows near 11°F.

Climate normals: NOAA 1991-2020 monthlies, WATERLOO MUNI AP station (8 mi away).

Geology at Black Hawk County

This spot sits on ground mapped as Cedar Valley Group that formed roughly 390 to 370 million years ago. Tough silica like agate and jasper typically survives weathering and collects as float in drainages and gravel.

Mapped unit: Cedar Valley Group
Age: 390–370 Ma (Middle Devonian to Late Devonian)
Elevation: 910 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.

Today's weather

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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.

Iowa Geological Survey
Iowa DNR state park rules
Community submissions reviewed against published agency rules

Found at Black Hawk County

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

Cold Water Agate Encyclopedia →

Nearby rockhounding spots

Other rockhounding spots within driving distance of Black Hawk County.

Riverview Recreation AreaBlack Hawk County, Iowa · 4 mi awayGeode
La Porte CityBlack Hawk County, Iowa · 14 mi awayAgate
BrandonBuchanan County, Iowa · 20 mi awayGeode, Fossil
Bremer CountyBremer County, Iowa · 21 mi awayCold Water Agate
Shell RockButler County, Iowa · 22 mi awayLake Superior Agate
Benton CountyBenton County, Iowa · 27 mi awayCold Water Agate
Fayette CountyFayette County, Iowa · 38 mi awayLake Superior Agate
Steamboat RiverHardin County, Iowa · 42 mi awayGeode

Across the state line from Black Hawk County

Black Hawk County 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.

Mississippi RiverCrawford County, Wisconsin · 66 mi awayPearl
CassvilleGrant County, Wisconsin · 66 mi awayAgate, Quartz
Prairie du ChienCrawford County, Wisconsin · 69 mi awayAgate
Grant River bedsGrant County, Wisconsin · 77 mi awayPearl

Black Hawk County FAQ

Where is Black Hawk County?+

Black Hawk County is in Black Hawk County, Iowa, at 42.52178, -92.25494. Nearest road: North Elk Run Road.

What rocks and minerals can you find at Black Hawk County?+

Black Hawk County is reported to produce Cold Water Agate.

Is collecting allowed at Black Hawk County?+

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 Black Hawk County?+

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 Black Hawk County?+

The most comfortable months at Black Hawk County are March to November.

How do I get to Black Hawk County?+

Open the directions link to navigate to 42.52178, -92.25494 in Google Maps. The nearest road is North Elk Run Road.

More rockhounding in Iowa

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