Franklin Furnace: Fluorite & Franklinite Rockhounding in Sussex County, New Jersey

Plan your visit

Generally open to casual rockhounding

County

Sussex County

State

New Jersey

Nearest road

Buckwheat Road

Postcode

07416

Coordinates

41.11625, -74.58734

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 Franklin Furnace

Comfortable months (45 to 90°F highs)

Best months: March to November. Typical highs run 83°F in midsummer and 35°F in midwinter, with winter lows near 17°F.

Climate normals: NOAA 1991-2020 monthlies, SUSSEX AP station (6 mi away), adjusted for elevation.

Geology at Franklin Furnace

This spot sits on Franklin Marble, mapped as marble that formed roughly 1600 to 1000 million years ago. Metamorphic terrain like this commonly hosts vein and replacement mineralization, and old workings typically mark the productive zones.

Mapped unit

Franklin Marble

Age

1600–1000 Ma (Mesoproterozoic)

Rock types

marble

Elevation

610 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