Zion: Jasper Rockhounding in Madison County, Missouri

Quick details

Access

Public area

County

Madison County

State

Missouri

Nearest road

County Road 319

Coordinates

37.42330, -90.28695

Geology at Zion

This spot sits on Eminence Dolomite, Potosi Dolomite, mapped as dolostone that formed roughly 495 to 485 million years ago. Chert and agate nodules typically form inside carbonate rock like this and weather out as tough, waxy lumps in soils and creek beds.

Mapped unit

Eminence Dolomite, Potosi Dolomite

Age

495–485 Ma (Furongian)

Rock types

dolostone

Elevation

860 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 Zion

Best months: February to December. Typical highs run 87°F in midsummer and 41°F in midwinter, with winter lows near 20°F.

Climate normals: NOAA 1991-2020 monthlies, FREDERICKTOWN station (9 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 Zion

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

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