Belle Mountain: Malachite & Cuprite Rockhounding in Mercer County, New Jersey

Plan your visit

Generally open to casual rockhounding

County

Mercer County

State

New Jersey

Nearest road

Valley Road

Postcode

08530

Coordinates

40.33598, -74.92486

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 Belle Mountain

Comfortable months (45 to 90°F highs)

Best months: March to December. Typical highs run 87°F in midsummer and 41°F in midwinter, with winter lows near 18°F.

Climate normals: NOAA 1991-2020 monthlies, LAMBERTVILLE station (2 mi away), adjusted for elevation.

Geology at Belle Mountain

This spot sits on Diabase, mapped as plutonic that formed roughly 200 to 145 million years ago. Plutonic rock like this weathers slowly into grus and boulders, and the most productive collecting is typically in weathered zones and drainages.

Mapped unit

Diabase

Age

200–145 Ma (Jurassic)

Rock types

plutonic

Elevation

270 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.

• New Jersey Geological and Water Survey
• Monmouth County Park System, fossil collecting rules
• Sterling Hill Mining Museum
• Community submissions reviewed against published agency rules