Best spot

Bells Mill Park: Calcite Rockhounding in Hamilton County, Iowa

Updated July 2026

Bells Mill Park preserves outcrops along the Boone River where dark, well-formed calcite crystals occur in the Mississippian carbonates, an unusual and distinctive Iowa mineral locality. Unlike the state's ubiquitous glacial agate, this is a bedrock mineral occurrence tied to one specific valley. The park's river frontage keeps loose material replenished in the Boone River gravels. Reported finds include calcite. Below: coordinates, access notes, nearby spots, and trip-planning links.

Bells Mill Park photos

Public image records connected to this spot or its reported material.

1 photo

A cobble gravel bar on the Boone River in Hamilton County, Iowa, near Bells Mill Park

Quick details

Access: Public area
County: Hamilton County
State: Iowa
Nearest road: Bell's Mill Road
Postcode: 50249
Coordinates: 42.34056, -93.89169

Geology at Bells Mill Park

This spot sits on ground mapped as lower Cherokee Group that formed roughly 325 to 305 million years ago. Fresh exposures, cuts, and drainages are typically the most productive places to look on ground like this.

Mapped unit: lower Cherokee Group
Age: 325–305 Ma (Pennsylvanian)
Elevation: 950 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 Bells Mill Park

Best months: March to November. Typical highs run 83°F in midsummer and 27°F in midwinter, with winter lows near 7°F.

Climate normals: NOAA 1991-2020 monthlies, WEBSTER CITY station (10 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 Bells Mill Park

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

Calcite Encyclopedia →

Nearby rockhounding spots

Other rockhounding spots within driving distance of Bells Mill Park.

Bells Mill Park FAQ

Where is Bells Mill Park?+

Bells Mill Park is in Hamilton County, Iowa, at 42.34056, -93.89169. Nearest road: Bell's Mill Road.

What rocks and minerals can you find at Bells Mill Park?+

Bells Mill Park is reported to produce Calcite.

Is collecting allowed at Bells Mill Park?+

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 Bells Mill Park?+

A rock hammer, sturdy gloves, safety glasses, and a collecting bag cover the basics here. Add a spray bottle: wet rock shows color and pattern that dry rock hides.

When is the best time to visit Bells Mill Park?+

The most comfortable months at Bells Mill Park are March to November.

How do I get to Bells Mill Park?+

Open the directions link to navigate to 42.34056, -93.89169 in Google Maps. The nearest road is Bell's Mill Road.

More rockhounding in Iowa

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Open Bells Mill Park on the map

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