Phillipsburg: Chrysocolla & Rhodochrosite Rockhounding in Granite County, Montana

Plan your visit

Generally open to casual rockhounding

County

Granite County

State

Montana

Nearest road

Granite Rd

Postcode

59858

Coordinates

46.31933, -113.28055

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 Phillipsburg

Comfortable months (45 to 90°F highs)

Best months: March to October. Typical highs run 79°F in midsummer and 34°F in midwinter, with winter lows near 14°F.

Climate normals: NOAA 1991-2020 monthlies, PHILIPSBURG RS station (1 mi away), adjusted for elevation.

Geology at Phillipsburg

This spot sits on Red Lion Formation, Hasmark Formation, Silver Hill Formation, and Flathead Sandstone, undivided, mapped as limestone, shale, dolomite, and quartzite that formed roughly 540 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

Red Lion Formation, Hasmark Formation, Silver Hill Formation, and Flathead Sandstone, undivided

Age

540–485 Ma (Cambrian)

Rock types

limestone, shale, dolomite, and quartzite

Elevation

5,730 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