Mt. Gilboa: Axinite & Prehnite Rockhounding in Hunterdon County, New Jersey

Updated June 2026

Mt. Gilboa is a mapped rockhounding spot in Hunterdon County, New Jersey. Reported finds include axinite, prehnite, epidote, datolite, tourmaline, and more. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Hunterdon County
State: New Jersey
Nearest road: Daniel Bray Highway
Postcode: 08530
Coordinates: 40.38978, -74.95619

Geology at Mt. Gilboa

This spot sits on Lockatong Formation, mapped as siltstone mudstone and sandstone mudstone that formed roughly 235 to 200 million years ago. Sedimentary rock like this erodes unevenly, so the most productive collecting is typically along fresh cuts, badland slopes, and active drainages.

Mapped unit: Lockatong Formation
Age: 235–200 Ma (Late Triassic)
Rock types: siltstone mudstone and sandstone mudstone
Elevation: 220 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 Mt. Gilboa

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.

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 Mt. Gilboa

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 Mt. Gilboa.

Across the state line from Mt. Gilboa

Mt. Gilboa is close enough to the New Jersey border that the next-closest rockhounding spots are in a neighboring state. Worth knowing if you are already on the road.

Mt. Gilboa FAQ

Where is Mt. Gilboa?+

Mt. Gilboa is in Hunterdon County, New Jersey, at 40.38978, -74.95619. Nearest road: Daniel Bray Highway.

What rocks and minerals can you find at Mt. Gilboa?+

Mt. Gilboa is reported to produce Axinite, Prehnite, Epidote, Datolite, Tourmaline, Actinolite, Zeolite.

Is collecting allowed at Mt. Gilboa?+

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 Mt. Gilboa?+

A rock hammer, a pry bar, gloves, and safety glasses suit pegmatite ground. Work weathered zones and check dump piles; coarse crystals often sit in decomposed rock.

When is the best time to visit Mt. Gilboa?+

The most comfortable months at Mt. Gilboa are March to December.

How do I get to Mt. Gilboa?+

Open the directions link to navigate to 40.38978, -74.95619 in Google Maps. The nearest road is Daniel Bray Highway.

More rockhounding in New Jersey

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Open Mt. Gilboa on the map

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