Bismark Mine: Molybdenite & Pyrite Rockhounding in Madison County, Montana

Plan your visit

Generally open to casual rockhounding

County

Madison County

State

Montana

Nearest road

Mammoth South Boulder Road

Coordinates

45.61285, -112.04897

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.

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 Bismark Mine

Comfortable months (45 to 90°F highs)

Best months: April to October. Typical highs run 75°F in midsummer and 25°F in midwinter, with winter lows near 3°F. At about 7,400 ft, snow can block access from late fall well into spring, so check conditions outside of summer.

Climate normals: NOAA 1991-2020 monthlies, TWIN BRIDGES station (14 mi away), adjusted for elevation.

Geology at Bismark Mine

This spot sits on Glacial moraine deposits, mapped as sand and gravel that formed within roughly the last 3 million years. Loose deposits like these are float-collecting ground: erosion keeps moving durable rocks and minerals into gravel bars, cutbanks, and washes.

Mapped unit

Glacial moraine deposits

Age

3 Ma to present (Pleistocene)

Rock types

sand and gravel

Elevation

7,400 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.

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.

State guidance last verified: April 1, 2026

• BLM Montana, Recreational mineral collecting
• Montana Bureau of Mines and Geology
• Gem Mountain Sapphire Mine (fee-dig operator)
• Community submissions reviewed against published agency rules