Old Mines: Barite & Calcite Rockhounding in Washington County, Missouri

Updated June 2026

Old Mines is a mapped rockhounding spot in Washington County, Missouri. Reported finds include barite, calcite, galena, goethite, malachite, and more. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Washington County
State: Missouri
Nearest road: MO 21;MO 47
Postcode: 63630
Coordinates: 38.01515, -90.75614

Geology at Old Mines

This spot sits on Eminence Dolomite, Potosi Dolomite, mapped as dolostone that formed roughly 495 to 485 million years ago. Carbonate rock like this dissolves and weathers readily, so fresh road cuts, quarries, and creek exposures are typically the most productive ground.

Mapped unit: Eminence Dolomite, Potosi Dolomite
Age: 495–485 Ma (Furongian)
Rock types: dolostone
Elevation: 810 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 Old Mines

Best months: February to December. Typical highs run 87°F in midsummer and 41°F in midwinter, with winter lows near 23°F.

Climate normals: NOAA 1991-2020 monthlies, POTOSI 4 SW station (9 mi away), adjusted for elevation.

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 Old Mines

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 Old Mines.

Across the state line from Old Mines

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

SpartaTop pick in IllinoisRandolph County, Illinois · 56 mi awayPyrite, Fossils

Old Mines FAQ

Where is Old Mines?+

Old Mines is in Washington County, Missouri, at 38.01515, -90.75614. Nearest road: MO 21;MO 47.

What rocks and minerals can you find at Old Mines?+

Old Mines is reported to produce Barite, Calcite, Galena, Goethite, Malachite, Marcasite, Pyrite, Chert, Quartz.

Is collecting allowed at Old Mines?+

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 Old Mines?+

A rock hammer, gloves, and safety glasses are enough for oxidized copper ground. Look for green and blue staining on weathered rock and in old dump piles.

When is the best time to visit Old Mines?+

The most comfortable months at Old Mines are February to December.

How do I get to Old Mines?+

Open the directions link to navigate to 38.01515, -90.75614 in Google Maps. The nearest road is MO 21;MO 47.

More rockhounding in Missouri

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Open Old Mines on the map

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